Sumsub — Travel Rule integration

Travel Rule is an exchange of participant data between two VASPs about one transfer. Sumsub is the hub: you talk to Sumsub, Sumsub talks to the counterparty over whichever protocol you both speak.

The integration is small. What makes it fail in production is that most integrations build one half of it — they start exchanges but never finalise them, or they answer the first question and not the second, and nothing in the API complains. This recipe is organised around those omissions.

⚠️ Sandbox tokens only

Do not accept or use a production App Token here. Travel Rule acts on real transfers and real counterparty VASPs, and a test exchange sent to a live counterparty puts a real request in a real compliance queue. Insist on a sandbox pair from https://cockpit.sumsub.com/checkus/home?sbx=true — Connect Sumsub to your AI agent -> Build & configure -> Generate token. Token + secret are revealed once; copy both before closing the dialog.

Deeper auth mechanics: sumsub-api-auth.

The three flows

Everything starts with one question: who creates the exchange, and has the transfer already settled on-chain?

                          who creates the exchange?
                  ┌────────────────────┬────────────────────┐
                  │        you         │   the counterparty │
   ┌──────────────┼────────────────────┼────────────────────┤
   │ not settled  │  ① before          │                    │
   │ yet          │    settlement      │   ③ you answer     │
   ├──────────────┼────────────────────┤     their request  │
   │ already      │  ② after           │                    │
   │ settled      │    settlement      │                    │
   └──────────────┴────────────────────┴────────────────────┘

	① before settlement	② after settlement	③ answering
Typical case	Your user is withdrawing	A deposit arrived with no data	Anything involving your user
`info.paymentTxnId`	empty	required	set by them
Blocking	yes — the withdrawal waits	no — funds already moved	their transfer waits on you
End state	`finished` after you link the hash	`finished`, automatically	`finished`, automatically

📘 Do not key your integration off info.direction. It says which way the money moves for the account you are looking at, and it is flipped between the two sides of the same exchange. Who created the exchange is the distinction that changes your code; direction is not.

⚠️ Flow ③ is not optional. Every VASP that starts exchanges also receives them, and an unanswered request means your user's transfer is delayed or refused by the counterparty's rules. Integrations that ship only ①/② are the single biggest source of Travel Rule failures.

Stage 0 — Preconditions

Check these before writing any code; each produces a confusing failure later.

Travel Rule entitlement on the tenant — verify with sumsub-check-permissions.
Your organisation is linked to a VASP. Without it, nothing starts and the error reads Your organization is not yet linked to a VASP. Please contact your Customer Success Manager. That is not a permissions problem and not retryable — relay it and stop. Linking is done by a Customer Success Manager, not over the API.
A Travel Rule rule bundle is installed and active. The bundle decides what each exchange outcome means for the transaction's review answer — the platform has no default opinion. See sumsub-create-kyt-rules.
Travel Rule settings are configured: confirmation timeout, ownership validation mode, participant data settings.
Webhooks are subscribed and reaching you — see sumsub-manage-webhooks. The events that matter here: applicantKytTxnCreated, applicantKytTxnApproved, applicantKytTxnRejected, applicantKytOnHold, applicantKytTxnAwaitingUser, applicantKytTxnDataChanged.
The Wallet Address Book has your addresses — both the ones you receive on and the ones you send from. See sumsub-manage-wallet-address-book.

Stage 1 — Identify the counterparty VASP

This single step moves the success rate more than anything else in the integration, and it is the one most often skipped.

Option A — let the user pick (recommended)

Add a destination selector to the withdrawal screen and pass the chosen id as counterparty.institutionInfo.internalId. Attribution is then skipped entirely and the request goes straight to the counterparty.

# search the directory as the user types
GET /resources/vasps/-?q=binance&limit=20

Search on q — people know brand names, not legal entities.
If they pick a group rather than one of its regional entities, that is fine: Sumsub resolves the group down to the entities underneath it that can actually receive the request. Do not force a choice between subsidiaries.
Hidden VASPs are excluded by default; test VASPs only exist in Sandbox, so no production filtering is needed.

Single VASP by id: GET /resources/api/vasps/{id}/one.

Option B — send only the address

Sumsub attributes it against the wallet address databases, then asks the Travel Rule protocols, then falls back to blockchain analytics providers. This is the right fallback when the user cannot name their destination, but a significant share of addresses cannot be attributed at all.

The two are not exclusive: offer the picker, allow proceeding without it.

Stage 2 — Submit the transfer

Build and post the transaction with sumsub-create-transaction using type: travelRule. Only two fields distinguish the flows:

	before settlement	after settlement
`info.paymentTxnId`	omit	the on-chain hash
`counterparty.institutionInfo.internalId`	VASP id from Stage 1, when known	same

📘 In flow ② check first that an exchange does not already exist for this transfer — a duplicate puts two requests in the counterparty's queue. Query GET /resources/kyt/txns/query/- walking the deduplication ladder — hash, then address + asset, then amount + time window — and create the exchange only when nothing comes back. Endpoint syntax, the ladder and helper scripts: references/find-transactions.md.

🚧 Sending a hash in flow ① turns it into an after-settlement exchange — the counterparty is asked to authorise a transfer that already happened. Omitting it in flow ② does the reverse. This one field decides the semantics.

Currencies and chains

Two currency facts change Travel Rule behaviour, not just precision.

A symbol is not an asset. USDT and USDC each name more than a dozen different assets in Sumsub's catalogue, and over a thousand symbols exist on more than one chain. Send currencyCode without cryptoParams.cryptoChain for one of those and the lookup matches nothing at all, so the asset is unresolved and no conversion happens.

Thresholds are compared against amountInDefaultCurrency. If that field is absent, the Travel Rule threshold check is skipped entirely and the flow runs regardless of amount — the same for the unhosted-wallet threshold. The value is also frozen when the transaction is created, so a bad conversion needs a backfill, not a re-read. Send amountInDefaultCurrency and defaultCurrencyCode explicitly whenever you know them.

📘 The counterparty's protocol has its own asset vocabulary, and only a minority of catalogue entries carry a mapping for any given protocol. An exotic token with no mapping cannot be expressed in the outgoing message and the exchange ends at notEnoughCounterpartyData before delivery. Check vocabulary coverage before debugging the payload.

Resolving symbols, chains and aliases: sumsub-resolve-currency.

Stage 3 — Read the outcome

Sumsub assigns a Travel Rule status, then your rules assign a review answer. They are different things and readers conflate them constantly: a transaction can be approved by your rules while its exchange sits at expired. Gate your withdrawal on the review answer, and record the exchange status for audit.

Read the transaction with ${CLAUDE_SKILL_DIR}/scripts/get_transaction.sh <txnId> (a signed curl — use the scripts rather than hand-rolling HTTP so signing and encoding stay right). Immediately after submission the exchange either waits or is already final:

Outcome	Meaning
`awaitingCounterparty`	Delivered; waiting on their answer
`counterpartyVaspNotFound`	Nobody to ask — treated as an unhosted wallet. Usually the largest single outcome by volume; see `references/unhosted-wallets.md`
`counterpartyVaspNotReachable`	Identified, but no shared protocol
`notEnoughCounterpartyData`	Your payload failed protocol validation — not their decline
`notApplicable`	Your configuration skipped it

Full status list, transitions and which ones are final: references/statuses.md.

Stage 4 — Finalise, or cancel

Only flow ① needs code here. Flows ② and ③ reach finished on their own.

# after you broadcast
${CLAUDE_SKILL_DIR}/scripts/finalize_txn.sh <txnId> <on-chain hash>
# → PATCH /resources/kyt/txns/{id}/data/info   { "paymentTxnId": "<on-chain hash>" }

# if the user abandoned the withdrawal instead
${CLAUDE_SKILL_DIR}/scripts/cancel_txn.sh <txnId>
# → POST /resources/api/tr/{id}/cancel

🚧 This is the most-skipped call in the whole integration. Without it the exchange stops at completed, the counterparty can never reconcile the data they hold against anything on-chain, and neither side has a complete record for audit. Send the hash as soon as you broadcast.

Cancelling matters too: an abandoned exchange left open occupies the counterparty's queue until it expires and records you as unresponsive.

Stage 5 — Answer incoming requests

A request arrives as applicantKytTxnCreated on a transaction where your user is data.applicant and the wallet to confirm is data.applicant.paymentMethod.accountId. Fetch it with ${CLAUDE_SKILL_DIR}/scripts/get_transaction.sh <txnId>.

Answering is two responses, in order. The transaction tells you which it still needs:

Flag	`true`	`false`
`needMasking`	send response one	already answered — skip
`travelRuleInfo.needApplicantOwnershipConfirmation`	send response two	already answered — skip

# response one — is this wallet ours?
${CLAUDE_SKILL_DIR}/scripts/confirm_ownership.sh <txnId> confirmed   # or unconfirmed
# → POST /resources/kyt/txns/{id}/ownership/confirmed

# response two — whose is it?
${CLAUDE_SKILL_DIR}/scripts/attach_applicant.sh <txnId> <applicantId>
# → POST /resources/kyt/txns/{id}/travelRuleOwnership  { "applicantId": "..." }
# an { "applicantParticipant": { ... } } body instead: attach_applicant.sh <txnId> - < body.json

🚧 Order is load-bearing, and getting it wrong fails silently. Response two on its own returns 200 — but while needMasking is true the exchange is pinned at onHold no matter what data you send, the counterparty never receives an answer, and the request expires. Confirming the address is also what unmasks the counterparty's data, so until response one lands there is nothing to reconcile against.

📘 No waiting between them. Both calls return the updated transaction, so there is nothing to re-read and no webhook to wait for.

If you see your transactions sitting at onHold, you are sending response one and not response two.

How long you have

Seconds, not minutes. The counterparty picks the confirmation timeout in their own settings, and the shortest value on offer is currently 10 seconds — the whole round trip, including webhook delivery and both calls, not your thinking time. It is not shown on the transaction and varies by counterparty, so design for the shortest rather than the typical.

Some protocols do not wait at all: the counterparty's system asks and expects the answer inside the same request, so whatever Sumsub can determine from your stored configuration at that instant is the answer. There is no window and no opportunity to answer by hand.

🚧 That is why automation is not an optimisation here. A manual process cannot cover the traffic, and you cannot tell in advance which kind of request is arriving.

Automating both responses

Automation does not replace the two responses — it pre-answers them, so requests arrive with the flags already false.

Register this	Pre-answers
Address in the Wallet Address Book	response one
Address as an applicant payment method	both

Neither works unless the ownership validation mode allows reuse — one setting, chosen in the dashboard. See Confirmation ownership mode and sumsub-manage-wallet-address-book.

Stage 6 — Test it in Sandbox

Sandbox provides a test VASP that answers like a real counterparty. Work outward from the success case so that when something breaks you know which change caused it, and rehearse the finalisation step specifically — it is the one integrations omit in production.

Procedure, trigger values and what is not reproducible in Sandbox: references/sandbox-testing.md.

sumsub-integrate-travel-rule