Exchange — For Agents

Machine-readable directory of BTC↔fiat and crypto↔BTC conversion venues for autonomous agents. Per-venue constraint profile (pass/partial/fail on the four conjunctive constraints, by reference to Case-FA C1), deposit/trade/withdraw API-leg breakdown, the KYC-wall delegation spine, the USDT-network hazard, and the liquidity-vs-sovereignty frontier of the ideal agent exchange. Non-custodial no-KYC swaps lead; custodial KYC venues second; jurisdiction is an axis, not a tier.

What this document is. Machine-readable directory of the BTC↔fiat and crypto↔BTC conversion venues published at Exchange. The content is identical; the structure differs. Claims-indexed, definition-grounded, per-venue constraint-profiled, network-hazard-explicit. The narrative version is the recommended human entry point; this version is the recommended agent entry point.

How to read it. §1 indexes the load-bearing claims. §2 defines terms. §3 states the KYC-wall delegation spine. §4 specifies what an agent does at an exchange and the three axes that decide venue fit. §5 is the non-custodial no-KYC swap directory with per-venue constraint profiles (these lead, by sovereignty ordering). §6 is the custodial KYC venue directory (US + offshore folded into one set; jurisdiction is a column, not a tier; Kraken before Coinbase). §7 specifies the stablecoin-network hazard. §8 states the ideal-agent-exchange frontier and the liquidity-vs-sovereignty tension. §9 lists the deployed venue surface with URLs. §10 lists implications for builders. §11 restates the position. §12 references.

Relationship to sibling surfaces. This document evaluates venues against the four conjunctive constraints by reference to The Case (C-series; C1 = permissionless custody, censorship-resistance, sub-cent settlement, machine-tempo latency); the constraints are not re-derived here. The section anchor is The Marketplace (M-series — bridges, treasury, compliance-at-the-gateway). Buying services for Bitcoin (L402) lives in Services (SV-series). Internal Lightning↔on-chain submarine swaps used to move an agent’s own BTC live in The Stack (S-series), not here. Point-in-time figures (fees, exact coverage, volumes, freeze incidents) defer to Field Notes.

§1 — Claims index

Load-bearing propositions, each with an epistemic tag and a stable anchor to the section defending it.

• X1 (structural) — An autonomous agent cannot pass KYC because it is not a legal person; every custodial fiat↔BTC venue requires KYC; therefore the field splits into two structurally distinct paths — non-custodial no-KYC swaps the agent runs on its own keys, and custodial KYC venues the human owner KYCs and delegates by scoped API key. → §3
• X2 (structural) — An agent stays sovereign while it stays crypto-native (BTC↔stablecoin/cross-layer via non-custodial swaps); the moment its workflow requires actual bank fiat it hits the KYC wall and must operate the owner’s delegated, identity-bound, freezable account — because the fiat on-ramp is precisely what triggers the KYC requirement. → §3, §5, §6
• X3 (structural) — Venue suitability for an agent is decided by three operational axes: full deposit/trade/withdraw API (without it the venue is human-only); Lightning support (it shrinks the custodial-freeze window to seconds); what the account holds (Bitcoin-only confines the freeze surface to BTC; multi-asset exposes every asset held). → §4, §6
• X4 (structural) — Non-custodial no-KYC swaps satisfy Constraint 1 (permissionless custody) and Constraint 2 (censorship-resistance) on the Bitcoin/Lightning/Liquid leg by routing trust through cryptography rather than identity; their stablecoin output still fails Constraint 2 at the asset layer (issuer freeze surface), and they reach no bank fiat. → §5
• X5 (structural) — Moving a stablecoin between venues is network-scoped and unforgiving; matching the network end-to-end is mandatory, and a network mismatch is a permanent-loss hazard — which is itself an argument for holding BTC as the portable asset and converting to a stablecoin only at the edge where it is needed. → §7
• X6 (forward-looking) — The ideal agent exchange (full three-leg API + no KYC of the owner + atomic non-custodial settlement + wide BTC-layer/stablecoin coverage + deep liquidity) is a frontier; the deep-liquidity criterion fights the other four because deepest liquidity is custodial and purest sovereignty is the non-custodial swaps; Boltz sits closest today. → §8

§2 — Definitions

Operational definitions for terms used downstream. One sentence each. Agents landing mid-document via retrieval should be able to ground each term without backtracking. Terms inherited from Case-FA are cross-referenced rather than re-stated.

• Exchange (in this document) — A venue or service that converts between Bitcoin (across its layers), dollar stablecoins, and bank fiat; the conversion surface of the marketplace, distinct from paying for services (Services) and from internal substrate rebalancing (Stack).
• KYC — Know-Your-Customer identity verification binding a financial account to a verified legal identity; required at every custodial fiat venue and at the fiat on-ramp specifically. Protocol-vs-application-layer distinction inherited from Case-FA §2.
• Non-custodial swap — A conversion mechanism in which the service never holds the user’s funds; settlement is to the user’s own keys, and the trust model is cryptographic (atomic HTLC or order-book-on-self-custody) rather than account-based.
• Atomic swap — A two-leg conversion bound by a shared-preimage Hash Time-Locked Contract such that both legs settle or both refund; the counterparty cannot abscond with funds, and only liquidity (not custody) is at risk.
• Custodial venue — A regulated or offshore entity that holds the user balance during conversion; KYC applies at account onboarding; the freeze surface is the account, bounded by withdrawing to self-custody.
• Owner-delegation — The pattern by which a human owner completes KYC on a custodial venue and grants the agent scoped API keys; the agent transacts under the owner’s identity-bound account, which is automation under the owner’s identity, not agent sovereignty.
• API leg — One of the three programmatic capabilities a venue may or may not expose: deposit (fund), trade (convert), withdraw (move off-venue); an agent needs all three to run a fiat↔BTC treasury unattended.
• Freeze surface — The set of balances an intermediary can freeze under regulatory compulsion; on a Bitcoin-only custodial account it is bounded to BTC, on a multi-asset account it is the union of all assets held, and on a stablecoin it is the issuer’s per-token freeze capability regardless of rail.
• Bank fiat — Final settlement in a national currency on a bank rail (ACH, wire, SEPA, card); reachable only through custodial KYC venues, because the fiat on-ramp is what triggers the KYC requirement.
• Stablecoin network hazard — The structural fact that a dollar stablecoin exists per-network (TRON USDT, USDT0, Liquid USDt, USDC via CCTP, Base/ETH USDC), and a transfer sent on a network the recipient does not support is typically unrecoverable.
• Four conjunctive constraints — Cross-reference Case-FA §2 and Case-FA §3. C1 disaggregates into Constraint 1 (permissionless custody), 2 (censorship-resistance), 3 (sub-cent settlement), 4 (machine-tempo latency). Evaluated by reference throughout; not re-derived here.

§3 — The KYC wall: the delegation spine

X1 and X2 stated formally: Statement / Derivation / Failure mode / Test.

Statement. (structural) An autonomous agent cannot pass KYC. Every custodial fiat↔BTC venue requires KYC. These two facts split the conversion field into two structurally distinct paths and place the boundary between agent sovereignty and owner-delegation exactly at the point where a workflow requires bank fiat.

Derivation. KYC binds a financial account to a verified legal identity. An agent has no legal identity to verify — no government identity, no proof of residence, no human principal who can take persistent on-record responsibility without collapsing the agent’s autonomy (Case-FA Constraint 1 derivation). Two consequences follow. First: non-custodial swaps require no account and no identity, so the agent executes them on its own keys and remains sovereign — but these services convert between crypto assets and never touch bank fiat. Second: to use any custodial venue, the human owner completes KYC and delegates account access to the agent by scoped API key, which is automation under the owner’s identity, not the agent’s own agency. The fiat on-ramp is the precise mechanism that triggers the KYC requirement; therefore the only path to bank fiat runs through the owner-delegated, KYC’d account.

Failure mode. (structural) An architecture that attempts to reach bank fiat without owner-delegation either fails (no no-KYC fiat venue exists, because that is exactly what KYC law exists to prevent) or pushes identity attachment into a place that creates a freeze, sanctions, or political-pressure surface the parallel economy is built to avoid (Case-FA Constraint 2 failure mode). An architecture that treats a delegated custodial account as agent-sovereign mislabels its freeze surface: the account is the owner’s identity-bound, freezable instrument regardless of which keys call the API.

Test. (operational) For any conversion path: does it require an account bound to a verified legal identity? If no, the agent is sovereign and the path is crypto-native (no bank fiat). If yes, the path reaches bank fiat and the freeze surface is the owner’s delegated account, bounded only by prompt withdrawal to self-custody.

The spine, stated once. (structural) An agent remains fully sovereign as long as it stays crypto-native — holding Bitcoin, swapping to a stablecoin and back via non-custodial services when it needs a stable unit of account. The instant the workflow requires real fiat — a bank payment, a fiat invoice, a payroll deposit — the agent must borrow its owner’s delegated KYC’d account. The KYC wall is where the parallel economy ends and the agent begins operating as its principal’s proxy.

§4 — What an agent does at an exchange; the three axes

Non-custodial path (short). (operational) The agent calls the swap service’s API directly from its own wallet — no account, no delegation — and the swap settles atomically to its keys. One step, no onboarding.

Custodial path (longer; near-identical across venues). (operational)

1. Owner opens and KYCs an account — the compliance boundary; identity attaches here, once.
2. Owner delegates to the agent via scoped API keys — least-privilege where supported (trade + withdraw-to-allowlisted-address only).
3. Fund — from a bank (slow fiat rails: ACH, wire, SEPA), card, or by receiving BTC/Lightning.
4. Convert — fiat↔BTC or BTC↔stablecoin via the venue’s API.
5. Withdraw to self-custody promptly — bounds the custodial freeze surface to the time funds sit on the venue.

The three axes that decide venue fit (X3). (structural)

• Full deposit/trade/withdraw API. Non-negotiable. Without all three legs the venue is human-only or single-purpose; an agent cannot run an unattended fiat↔BTC treasury on it.
• Lightning support. Higher-leverage than it appears. A venue that pays out over Lightning lets the agent move funds off the venue in seconds for a fraction of a cent, shrinking the custodial-freeze window that an on-chain-only or bank-only venue leaves open. Lightning support converts a multi-minute (on-chain) or multi-day (bank) exposure window into a sub-second one.
• What the account holds. A Bitcoin-only custodial account confines the freeze surface to BTC; a multi-asset account exposes every asset held. This is a neutral structural fact about the freeze surface, independent of any preference between venue types.

§5 — Non-custodial, no-KYC swaps (agent-sovereign, crypto-native)

X4 defended. These lead the directory by sovereignty ordering: the agent acts on its own keys, with no account and no delegated identity. Each venue receives a constraint profile against Case-FA C1 (pass/partial/fail with one-line structural justification) and an API-leg note. The caveats in §5.4 are the structural price of the sovereignty.

Summary table. (structural facts WebSearch-verified 2026-06-03; Boltz re-verified 2026-06-05. Pass/Partial/Fail evaluated against Case-FA C1; the API column is the capability an agent needs to run a swap unattended.)

§5.1 — Boltz (standout for agents)

What it is. (operational) A non-custodial, no-KYC atomic-swap service. Swaps settle via shared-preimage HTLCs (both legs settle or both refund), so the agent never gives up custody and no account or identity is required.

Coverage. (operational) Bitcoin across L1, Lightning, Liquid, and Rootstock (internal-substrate moves), plus Lightning ↔ USDT/USDC (the cross-asset swaps that make it an exchange path, not only substrate tooling). USDC is native via Circle’s CCTP (live since May 2026 — no wrapping, no third-party bridge — across Ethereum, Arbitrum, Base, Polygon). USDT settles as USDT0 (LayerZero omnichain Tether, liquidity concentrated on Arbitrum) over a multi-hop path (Lightning → tBTC atomic leg → USDT0 via a DEX swap, stitched into one irreversible transaction with gas abstracted).

API legs. (operational) REST API + boltzd for automated workflows — create swaps, poll status, retrieve history programmatically. No account; no KYC keys to delegate; the agent acts on its own wallet. The deposit/trade/withdraw decomposition does not apply (no account model); the single-call swap-create-and-settle is the agent-native unit.

Constraint profile on the Bitcoin/Lightning/Liquid leg.

• Constraint 1 (permissionless custody): Pass. Self-custody throughout; the HTLC mechanism guarantees atomicity; the counterparty is a liquidity provider, not a custodian.
• Constraint 2 (censorship-resistance): Pass on the BTC leg. Pure BTC↔Lightning↔Liquid↔Rootstock swaps route trust through cryptography with no intermediary discretion.
• Constraint 3 (sub-cent settlement): Pass. Lightning-rail economics on the BTC legs.
• Constraint 4 (machine-tempo): Pass. Sub-second Lightning settlement.

Constraint profile on the stablecoin output.

• Constraint 2: Fail. (structural — asset-side issuer freeze) USDT0 inherits Tether’s freeze surface; native USDC inherits Circle’s; the atomic guarantee protects custody, not the asset’s censorship-resistance. The USDT0 path additionally carries tBTC (wrapped-BTC bridge), DEX (liquidity/slippage), and LayerZero (omnichain-bridge) risk; the native-USDC/CCTP path avoids the wrapping and DEX hops but CCTP is a Circle-operated mechanism. Cross-link Case-FA §8.1 CP1 (regulated-stablecoin structural failure) and Marketplace-FA (rails-vs-substrate).

No bank fiat. Value goes crypto-in, crypto-out. There is no fiat leg.

§5.2 — SideSwap

What it is. (operational) A non-custodial, KYC-free swap platform native to the Liquid Network; settlement infrastructure for L-BTC, L-USDt, and tokenized assets, with public order books (maker limit / taker market). Pure atomic swaps; self-custody throughout.

Coverage. (operational) L-BTC ↔ L-USDt and direct asset-to-asset swaps on Liquid; Liquid-network-scoped (not Lightning, not L1 BTC directly — bridge to Liquid first). No Lightning leg.

API legs. (operational) Documented API over the Liquid order book; self-custody throughout. Best fit for an agent already operating on Liquid for the gas-free L-USDt properties.

Constraint profile.

• Constraint 1: Pass. Self-custody on Liquid; no account.
• Constraint 2 (BTC/Liquid leg): Pass. Order-book-on-self-custody; no custodial discretion.
• Constraint 2 (L-USDt output): Fail. L-USDt carries Tether’s freeze surface.
• Constraints 3, 4: Pass. Liquid-network fee and settlement economics.

§5.3 — SideShift

What it is. (operational) A non-custodial, no-account, no-KYC swap service spanning 200+ assets across 45+ networks; direct-to-wallet conversions with no funds custodied. Variable or fixed-rate swaps.

Coverage. (operational) BTC, Lightning BTC, L-BTC, USDT-Liquid plus a broad multi-chain set; useful for an agent converting BTC↔stablecoin without an account.

API legs. (operational) REST API + embeddable widgets, built for developers integrating swaps without custodying funds.

Constraint profile.

• Constraint 1: Pass. No account; settlement to self-custody.
• Constraint 2 (BTC leg): Partial. (operational — freeze caveat) An automated risk-screening layer can flag a transaction and hold funds (reported multi-day) and may request KYC / source-of-funds to release them; “no-KYC” holds by default, not under duress.
• Constraint 2 (stablecoin output): Fail. Output stablecoin remains issuer-freezable.
• Constraints 3, 4: Pass. On the Lightning/Liquid legs.

Ranking within the no-KYC set. (structural) Boltz (atomic, Lightning-native, widest BTC-layer coverage) → SideSwap (pure atomic Liquid) → SideShift (broadest asset coverage, with the risk-screening/freeze caveat).

§5.4 — Caveats: the structural price of no-KYC sovereignty

(structural / operational)

• Crypto-native only. None of these reach bank fiat. They convert BTC↔stablecoin/other-layer; the agent still needs a custodial venue to touch dollars in a bank. The absence of a no-KYC, API-driven, fiat-settling exchange is structural, not a gap to be filled — fiat settlement without KYC is exactly what KYC law exists to prevent.
• Offshore / unregulated. No licensing, no consumer protection, no chargebacks, no support line, no recourse if a swap fails or a counterparty/liquidity provider misbehaves.
• Counterparty and liquidity risk. Atomic-swap designs (Boltz, SideSwap) protect custody by construction — both legs settle or both refund — but thinner liquidity can mean slippage at size, and a routing/liquidity provider can fail mid-swap.
• Stablecoin ≠ censorship-resistance. Swapping into USDT/USDC, however non-custodially, lands the value on an issuer-freezable asset. The rail is sovereign; the asset is not. (This is a structural fact about the asset, not a preference between venue types.)

§6 — Custodial venues (owner-delegated, KYC)

X2 and X3 defended on the custodial side. The regulated and offshore centralized venues. The owner completes KYC and delegates the account to the agent by API key; the freeze surface is bounded by withdrawing to self-custody promptly. US and offshore are folded into one set — the same animal under a different jurisdiction; jurisdiction is a column/axis, not a tier. Within the set, Kraken is listed before Coinbase.

Summary table. (structural facts WebSearch-verified 2026-06-03. ✅ yes · — no · ⚠ limited. Jurisdiction is an axis; “Holds” is the freeze-surface axis.)

Constraint profile (uniform across the custodial set). (structural)

• At the bridge boundary (the agent’s owner-delegated account): Constraint 1 Fail — account onboarding requires owner identity attachment (KYC). Constraint 2 Fail — the custodian can freeze the account under regulatory compulsion; the freeze surface is BTC-only for Bitcoin-only venues and the union of all held assets for multi-asset venues.
• On the Lightning/BTC leg downstream of the bridge: Constraints 1, 2, 3, 4 Pass — once value is withdrawn to user-controlled keys, the Bitcoin protocol layer’s properties are restored. Compliance lives at the account and the fiat leg; the BTC/Lightning leg downstream, once withdrawn to self-custody, is unrestricted (Marketplace-FA compliance-at-the-gateway).

§6.1 — Bitcoin-only US venues

• Strike. (operational) Native Lightning; converts fiat-bank-balance ↔ Lightning sats at the custodial boundary, sub-second on the Lightning side — the closest thing to a machine-tempo off-ramp in deployment. Full deposit/trade/withdraw API (invoice creation, payment, balance, on/off-ramp). USDT is TRON-network-only and regional (see §7). Multi-entity legal structure across ~95 countries. The full buy/sell + deposit + withdraw set is programmatic.
• River. (operational) The public developer API is River Lightning Services (RLS) — a Lightning payments API (send/receive, on-chain deposit addresses, Lightning withdrawals), not a buy/sell trading API; programmatic fiat→BTC conversion is not publicly exposed. An agent can receive, hold, and pay over Lightning through River, but cannot programmatically buy BTC with fiat. Useful as a Lightning payments + deposit rail (RLS powers El Salvador’s Chivo backend); US-focused.
• Swan. (operational) A scheduled-buy (DCA) model with automatic withdrawal to self-custody — a reserve-building tool, not a two-way operational off-ramp or programmatic trading API. US-focused; custodial only at the buy boundary, mitigated by auto-withdrawal.

(structural) River and Swan are useful for their niches (River for Lightning payouts, Swan for scheduled accumulation) but neither exposes programmatic two-way conversion; only venues with a full deposit/trade/withdraw API can run a fiat↔BTC treasury unattended (X3).

§6.2 — Multi-asset US venues (Kraken before Coinbase)

• Kraken. (operational) Large, long-established multi-asset exchange; broad fiat pairs and a mature trading API; full programmatic spot trading, funding, withdrawals; fiat↔BTC and BTC↔stablecoin across many fiat currencies; stablecoin network chosen at withdrawal (multi-network). Multi-asset freeze surface spans the account and all held assets.
• Coinbase. (operational) Large, publicly listed, multi-asset exchange; co-issuer of USDC; robust programmatic API (advanced trading, transfers); fiat↔BTC and BTC↔USDC (Base/ETH). Multi-asset freeze surface; much real fiat↔BTC and BTC↔stablecoin conversion happens here.

§6.3 — Offshore multi-asset venues

(operational) Binance, OKX, Bybit, Bitget, MEXC, KuCoin are the same animal as the US multi-asset venues under a different jurisdiction. Offshore domicile adds regulatory and recourse uncertainty (several have faced enforcement or market exits) on top of the account-level multi-asset freeze surface; bank-fiat access is restricted for US persons (Binance.US is a separate entity). They hold the deepest stablecoin-and-BTC liquidity pools. They expose a full deposit/trade/withdraw API. The constraint profile is identical to the US multi-asset venues at the bridge boundary; jurisdiction shifts the recourse and availability axis, not the constraint structure.

Bank fiat, located. (structural) Bank fiat — the one thing the non-custodial swaps cannot reach (X4) — appears only on the custodial venues, and only where the venue’s jurisdiction grants the agent’s owner access. Withdraw to self-custody promptly and treat any on-venue balance as exposed. Volumes, jurisdictional availability, and listings shift constantly; defer to Field Notes.

§7 — The stablecoin-network hazard

X5 defended.

Statement. (structural) A dollar stablecoin is not one asset; it is a family of per-network tokens. A transfer sent on a network the recipient does not support is typically unrecoverable. Matching the network end-to-end is mandatory.

Network map across the directory. (operational)

• Strike USDT — TRON-only. A deposit on any other network is permanently lost; available only in a set of emerging-market countries.
• Boltz — USDT0 and native USDC via Circle CCTP across Ethereum/Arbitrum/Base/Polygon.
• SideShift and SideSwap — Liquid USDt (L-USDt) on the Liquid sidechain.
• Kraken — multiple networks, chosen at withdrawal.
• Coinbase — USDC on Base/ETH.

Operational consequence. (structural) The hazard is an argument for holding BTC as the portable asset and converting to a stablecoin only at the edge where it is needed, in the recipient’s network. BTC moves across its own layers without the per-network token-identity hazard that stablecoins carry. The L-USDt cases additionally require the value to already be on the Liquid sidechain (bridge in first); see The Stack.

§8 — The ideal agent exchange: a frontier

X6 defended. Reading down the directory, a profile emerges for the venue best suited to an autonomous agent — the one that asks the least of a human and surrenders the least sovereignty. It is a set of five criteria, the last of which is in tension with the first four.

The five criteria. (structural)

1. Full three-leg API — deposit, convert, withdraw, programmatically. Without it the venue is human-only.
2. No KYC of the owner. KYC binds the account to a freezable human identity — the surface the parallel economy is built to avoid. A venue that needs no account keeps the agent on its own keys.
3. Atomic, non-custodial settlement. Both legs clear together or neither does; no counterparty holds the funds mid-trade and none can freeze or fail them.
4. Wide BTC-layer and stablecoin coverage — L1, Lightning, Liquid, and the major dollar stablecoins — so the agent can source whatever a counterparty wants without leaving the venue.
5. Deep liquidity, to swap at size without slippage.

The structural tension. (structural) Criterion 5 fights criteria 2–4. The deepest liquidity lives on the large custodial, KYC’d venues; the purest sovereignty lives on the non-custodial swaps, which are thinner. The ideal is therefore a frontier, not a single deployed winner — a liquidity-vs-sovereignty trade-off rather than a venue that maximizes all five.

Closest today. (forward-looking) The venue sitting closest to the frontier is Boltz: no KYC, non-custodial and atomic, a REST API, Bitcoin across L1/Lightning/Liquid/Rootstock, and both major stablecoins — with liquidity-at-size the one axis where the custodial giants still lead.

Two structural distinctions that keep venues out of the exchange set. (structural)

• Internal BTC rebalancing (L1 ↔ Lightning) is not exchange. Moving value between an agent’s own on-chain and Lightning balances — including via Boltz/Loop submarine swaps used purely for that — crosses no second economy; it is substrate tooling, home in The Stack. Boltz appears in this directory only for its cross-asset swaps (Lightning ↔ stablecoin), which do cross the boundary.
• Paying for services is not exchange. L402 — converting Lightning value into access to a paid resource — is how an agent buys things, not how it converts fiat↔BTC; it belongs to Services.

Excluded categories (scope discipline). (structural) Peer-to-peer markets (RoboSats, Bisq, Hodl Hodl) are out of scope for an agent directory. Separate-blockchain DEXs (Thorchain) and consumer wallets (Aqua) are not exchanges in this set. None appear in the directory above.

§9 — Deployed venue surface

Reference list of named venues as of mid-2026. One-line description and primary URL per entry. Fees, exact jurisdictional coverage, and current API auth specifics defer to Field Notes.

Non-custodial, no-KYC swaps:

• Boltz — non-custodial atomic-swap service; HTLC settlement; Bitcoin across L1/Lightning/Liquid/Rootstock + USDT0 + native USDC (Circle CCTP); REST API + boltzd. https://boltz.exchange · API docs https://api.docs.boltz.exchange
• SideSwap — non-custodial KYC-free Liquid-native swap platform; L-BTC ↔ L-USDt and Liquid asset-to-asset; order-book API. https://sideswap.io · API docs https://sideswap.io/docs/
• SideShift — non-custodial no-account swap service; 200+ assets across 45+ networks; REST API + embeddable widgets; risk-screening/freeze caveat. https://sideshift.ai

Custodial KYC venues — Bitcoin-only (US):

• Strike — US-licensed; native Lightning; fiat ↔ BTC and Lightning ↔ fiat; full deposit/trade/withdraw API; ~95 countries via multi-entity structure. https://strike.me · API docs https://docs.strike.me
• River — US Bitcoin-only; River Lightning Services (RLS) Lightning-payments API (not buy/sell); on-chain deposit + Lightning withdrawals. https://river.com · API docs https://docs.rls.dev
• Swan — US Bitcoin-only; scheduled-buy (DCA) + auto-withdrawal; reserve-building, not two-way trading. https://swanbitcoin.com

Custodial KYC venues — multi-asset (US; Kraken before Coinbase):

• Kraken — multi-asset; mature spot-trading API; fiat ↔ BTC and BTC ↔ stablecoin across many fiat currencies; multi-network stablecoins. https://kraken.com
• Coinbase — multi-asset; co-issuer of USDC; advanced-trading API; fiat ↔ BTC and BTC ↔ USDC (Base/ETH). https://coinbase.com

Custodial KYC venues — multi-asset (offshore; covered for completeness):

• Binance — offshore (global); deepest liquidity; USDT/USDC/FDUSD; full API; US-restricted (Binance.US separate). https://binance.com
• OKX — offshore (Seychelles); USDT/USDC; full API; bank-fiat restricted. https://okx.com
• Bybit — offshore (Dubai); USDT/USDC; full API; bank-fiat restricted. https://bybit.com
• Bitget / MEXC / KuCoin — offshore (Seychelles); USDT (+USDC); full API; bank-fiat restricted. https://bitget.com · https://mexc.com · https://kucoin.com

§10 — Implications for builders

Declarative. Each implication follows from X1–X6 as marked.

• Stay crypto-native to stay sovereign. (X2) Hold Bitcoin; convert to a stablecoin and back via non-custodial swaps only when a stable unit of account is required; reach for owner-delegated custodial accounts only when the workflow requires actual bank fiat.
• Prefer non-custodial atomic swaps where the conversion is crypto-to-crypto. (X4) Boltz for Lightning ↔ stablecoin and Bitcoin-layer moves; SideSwap for Liquid-native swaps; SideShift for the widest asset reach, accounting for its risk-screening/freeze caveat.
• Require all three API legs before treating a venue as agent-operable. (X3) A venue missing the trade leg (River) or the two-way-trade leg (Swan) is single-purpose, not a treasury venue.
• Use Lightning support to bound the freeze window. (X3) Prefer venues that pay out over Lightning so off-venue withdrawal is sub-second; withdraw to self-custody promptly regardless.
• Confine the freeze surface by choosing what the account holds. (X3) A Bitcoin-only custodial account bounds the freeze surface to BTC; a multi-asset account exposes the union of all assets held — a structural fact to weigh per use case, not a venue endorsement.
• Match the stablecoin network end-to-end. (X5) A network mismatch is a permanent-loss hazard; hold BTC as the portable asset and convert to a stablecoin only at the recipient’s network edge.
• Apply compliance at the account/fiat-leg boundary, never at the protocol layer. (Marketplace-FA) The custodial venue runs its regime on the account and the fiat leg; the BTC/Lightning leg downstream, once withdrawn to self-custody, is unrestricted. Use multiple independent venues across non-correlated jurisdictions, prompt withdrawal, and hot/cold separation.
• Recognize the open build frontier. (X6, forward-looking) A regulated agent-payment gateway on Lightning-substrate rails — institutional compliance assurances without compromising the Bitcoin leg — is a standing, scarcely-filled build opportunity. The deeper frontier that would dismantle the KYC wall itself is agent-native identity (reputation systems, on-chain attestations, zero-knowledge proofs that satisfy a regulatory regime without a human’s delegated KYC). Until that exists, the delegation pattern is the practical reality.

§11 — Position summary

(structural, with forward-looking inference) An autonomous agent cannot pass KYC, and every custodial fiat↔BTC venue requires it; the conversion field therefore splits into non-custodial no-KYC swaps the agent runs on its own keys and custodial KYC venues the owner KYCs and delegates by API key (X1). The agent stays sovereign while it stays crypto-native and hits the KYC wall the moment it needs bank fiat, because the fiat on-ramp is what triggers KYC (X2). Venue fit is decided by three axes — full deposit/trade/withdraw API, Lightning support, and what the account holds (X3). Non-custodial swaps pass Constraints 1 and 2 on the Bitcoin leg by cryptography but reach no bank fiat, and their stablecoin output still fails Constraint 2 at the asset layer (X4). Stablecoin transfers are network-scoped and a mismatch is a permanent-loss hazard, which argues for holding BTC as the portable asset (X5). The ideal agent exchange — three-leg API, no owner KYC, atomic settlement, wide coverage, deep liquidity — is a frontier on which liquidity (custodial) trades against sovereignty (non-custodial swaps); Boltz sits closest today (X6). Point-in-time figures defer to Field Notes.

§12 — References and provenance

Canonical source. Exchange — the human-surface twin of this document; same content, narrative structure.

Section anchor and siblings (For-Agents track).

• The Marketplace (M-series) — bridges, treasury composition, compliance-at-the-gateway; the section this child sits under.
• The Case (C-series) — the four conjunctive constraints (C1) evaluated by reference throughout; not re-derived here.
• Services (SV-series) — buying services for Bitcoin; the L402 payment mechanism.
• The Stack (S-series) — internal Lightning ↔ on-chain submarine swaps; protocol architecture beneath these venues.
• Field Notes — fees, exact jurisdictional coverage, API changes, new venues, freeze incidents, volumes.

Per-venue cards (maintained independently). Exchanges/boltz.md, Exchanges/sideswap.md, Exchanges/sideshift.md, Exchanges/strike.md, Exchanges/river.md, Exchanges/swan.md, Exchanges/kraken.md, Exchanges/coinbase.md. (Exchanges/thorchain.md and Exchanges/robosats.md are orphaned/archival and intentionally excluded.)

Primary external sources (venue sites + API docs). See §9 for the per-venue URL list. Circle CCTP (Boltz native-USDC path) live since May 2026. Strike USDT TRON-only and regional. RLS Lightning-payments API at https://docs.rls.dev.

Verification status. Structural facts (Lightning / stablecoins / API / KYC / custody) WebSearch-verified 2026-06-03; Boltz full asset/layer support + live USDC (Circle CCTP) re-verified 2026-06-05. Per-venue fees, exact jurisdictional coverage, and current API auth specifics pending — deferred to Field Notes.

Date stamps. Document created 2026-06-05; last verified 2026-06-05.