End-to-end recipe for integrating Sumsub ID Connect — the OIDC-based "Verify with Sumsub ID" flow that lets a user share previously-verified identity claims with your app. TRIGGER when the user asks to "integrate Sumsub ID Connect", "add Verify-with-Sumsub-ID button", "reuse Sumsub KYC via OIDC", "exchange the Sumsub authorization code", "mint a Sumsub ID share token", or asks how to wire up `@sumsub/id-connect`, the OIDC `code → access_token` exchange (`/api/snsId/oauth/token`), the share-token / partner-consent flow, or the share-link redirect. Covers preconditions checklist, automated preflight, frontend button (library button + raw redirect alternative), backend code-for-token exchange, share-token minting, partner-consent shareLink flow, and applicant materialisation through `/resources/api/reusableIdentity/reuse`. SKIP for the standalone WebSDK / KYC widget (use `sumsub-integrate-websdk`), or for plain Reusable-KYC-via-API where the donor and recipient are both your own tenants without a user-mediated O
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End-to-end recipe for integrating Sumsub ID Connect — the OIDC-based "Verify with Sumsub ID" flow that lets a user share previously-verified identity claims with your app. TRIGGER when the user asks to "integrate Sumsub ID Connect", "add Verify-with-Sumsub-ID button", "reuse Sumsub KYC via OIDC", "exchange the Sumsub authorization code", "mint a Sumsub ID share token", or asks how to wire up `@sumsub/id-connect`, the OIDC `code → access_token` exchange (`/api/snsId/oauth/token`), the share-token / partner-consent flow, or the share-link redirect. Covers preconditions checklist, automated preflight, frontend button (library button + raw redirect alternative), backend code-for-token exchange, share-token minting, partner-consent shareLink flow, and applicant materialisation through `/resources/api/reusableIdentity/reuse`. SKIP for the standalone WebSDK / KYC widget (use `sumsub-integrate-websdk`), or for plain Reusable-KYC-via-API where the donor and recipient are both your own tenants without a user-mediated OIDC step.
allowed-tools
Read, Write, Bash
Sumsub — ID Connect integration
Embed the "Verify with Sumsub ID" OIDC flow end-to-end — preconditions →
preflight → button → backend exchange → consent → applicant in your workspace.
⚠️ Sandbox tokens only
Do not use a production App Token / secret while wiring this up. Insist on
a sandbox pair from
https://cockpit.sumsub.com/checkus/devSpace/appTokens — toggle the workspace
to Sandbox first, then Create. Token + secret are revealed once at
creation; copy both before closing the dialog. The preflight enforces this
with an sbx: prefix check.
⛔ Order of operations — do NOT scaffold an app first
This is the single most important rule of this skill. Write no frontend or
backend code, create no demo project, scaffold nothing until BOTH gates below
are green. The client-side Sumsub setup (Stage 0a) is manual and cannot be done
by you — jumping to code before it exists produces an app that can't
authenticate, can't redirect, and can't reuse. Always follow this sequence:
Confirm Stage 0a preconditions with the user — one by one. Do not assume
any item is done. For each, ask the user whether it exists; if it doesn't,
stop and hand them the exact manual step and where to do it (the support
email template, the Dev Space → OIDC Settings registration, the App Token
minting page, the level creation hand-off). These are Sumsub-dashboard /
support actions only — there is no public API for them, so you cannot do them
for the user. Wait until every item is confirmed before moving on.
Run Stage 0b preflight and require exit 0. Only after the preconditions
are confirmed, run scripts/preflight.sh. Resolve
every FAIL (loop back to Stage 0a as needed). Do not proceed on any FAIL.
Only now build. With both gates green, proceed to Stage 1 and scaffold
the frontend/backend.
If the user says "just build the demo" before the gates are green, briefly
explain why it won't work yet and walk them through the missing precondition
first. The code is the last step, not the first.
What ID Connect is (and isn't)
Sumsub ID Connect lets a business request specific verified identity claims —
age, name, nationality, email, country of residence, humanness — from a
Sumsub ID account belonging to the end-user. Sumsub hosts the entire
user-facing flow: sign-in, account creation (if needed), email OTP, any
missing verification steps, and a per-recipient consent screen. Your app
receives the result as a signed OIDC token plus, optionally, an applicant
materialised in your workspace through Reusable KYC.
This is not the WebSDK. The WebSDK runs a full KYC capture inside your
page; ID Connect delegates the whole UX to Sumsub.
The "Enable Sumsub ID Connect" toggle, OIDC client registration
(client_secret + redirect_uri allowlist), and sharing-partner registration
are Sumsub dashboard UI only — no public-API equivalent.
Stage 0a — Preconditions checklist
Before any code or preflight, the following must already exist on the Sumsub
side. Each item maps to a check below or to a runtime failure if missed.
Sumsub support has enabled ID Connect for your workspace. This is
not a self-serve toggle — until support flips it, no OIDC client
can be created and the preflight will report
connect_token: ID Connect not enabled for this workspace. Email your
CSM or support@sumsub.com first and wait for confirmation. Template:
```
Subject: Enable Sumsub ID Connect for clientId <YOUR_CLIENT_ID> (sandbox)
Hi Sumsub team,
Please enable Sumsub ID Connect for our workspace.
Environment: sandbox
clientId: <YOUR_CLIENT_ID> (Dashboard top-left)
Intended scopes: openid, share, name (adjust as needed)
Intended recipients: self (or list partner clientIds)
Use case: <one-line description of where the button will live>
Once enabled we'll register the OIDC client + redirect URIs in
Dev Space → OIDC Settings.
Thanks
```
App Token + secret (sandbox). Minted at
https://cockpit.sumsub.com/checkus/devSpace/appTokens with workspace
toggled to Sandbox. Both values shown once at creation. → exported as
SUMSUB_APP_TOKEN / SUMSUB_SECRET_KEY.
OIDC client registered at Dashboard → Dev Space → OIDC Settings.
Capture all three:
- client_id (public — goes in the browser, used as forClientId
for the share token in the common self-recipient case)
- client_secret (shown ONCE at creation; if you lose it you must
regenerate, which invalidates existing integrations). Required for the
Stage 2 code→token exchange — keep it server-side only.
- redirect_uri allowlist populated for BOTH callbacks (Sumsub
matches byte-for-byte — trailing slash, casing, port, query all
matter):
- your authorize callback (e.g. https://yourapp.com/auth/callback)
- your shareLink callback (e.g. https://yourapp.com/share-complete)
Sumsub redirects the browser back to these URLs and requires
public HTTPS — a bare http://localhost:3000 won't work for local
testing. To develop on your machine, expose your local server with a
public HTTPS tunnel (ngrok) and allowlist that origin — see
Local development with ngrok below.
At least one verification level exists in this workspace. Capture
levelName. If none, hand off to
sumsub-create-level first — Stage 4
can't materialise an applicant without one.
At least one Sumsub ID account with verified data for end-to-end
testing. An email-only account (no completed KYC) makes Stage 4 fail
with errorCode 10521 reusable-kyc-inactive-sumsub-id-account — see
the error table at the end of Stage 4.
Stage 0b — Preflight
scripts/preflight.sh machine-validates the
preconditions that can be probed without minting OIDC codes or creating
applicants. It does not mutate anything.
Checks (each independent — one failing doesn't abort the others):
Check
What it proves
connect_token
App-Token HMAC signing is accepted and ID Connect is enabled for the workspace — probes the endpoint with a known-bad code and expects 401 Invalid code (a 404 invalid clientId means ID Connect isn't enabled). This is a connectivity/entitlement probe, not the Stage 2 exchange route.
oidc_discovery
https://id.sumsub.com/.well-known/openid-configuration returns a valid OIDC discovery doc
levels
At least one verification level exists in this workspace
Exit code: 0 on all-PASS / PASS+WARN, 10 on any FAIL. Resolve all FAILs
before Stage 1.
Local development with ngrok
ID Connect can't be tested against http://localhost. Sumsub redirects the
browser back to your redirect_uri after the authorize flow (Stage 1) and
after the shareLink consent flow (Stage 3b), and it requires the URL to be
public HTTPS and present in the OIDC client's redirect_uri allowlist
byte-for-byte. A bare localhost URL is neither public nor HTTPS, so the
redirect fails. For local development, put a public HTTPS tunnel in front of
your local server with ngrok and allowlist that origin.
Start your backend locally (the example listens on PORT=3000):
PORT=3000 node examples/express-callback.js
Open a tunnel to that port. Prefer a reserved (static) domain so the
URL survives restarts — a free random ngrok URL changes on every launch and
forces you to re-edit the allowlist each time:
Point the app at the public URL, not localhost. The browser's
redirect_uri and the server-side shareLink redirectUri must derive from
the same public origin, so set PUBLIC_BASE_URL and restart:
Then open the ngrok URL (not localhost:3000) in the browser so the
redirect_uri it sends matches the allowlist.
⚠️ Re-register on every URL change. If you use an ephemeral ngrok URL,
the allowlist entry (and PUBLIC_BASE_URL) must be updated each time ngrok
restarts. A reserved domain avoids this churn.
ngrok's free interstitial ("You are about to visit…") only affects API/XHR
calls, not top-level browser navigation, so it doesn't block the OIDC
redirects. A reserved domain or paid plan removes it entirely.
Stage 1 — Frontend: the button
⛔ Gate. Do not start this stage until Stage 0a preconditions are all
confirmed with the user AND Stage 0b preflight exits 0. If you haven't done
both, go back — see "Order of operations" above. This is the first stage
where you write code; everything before it is setup you must verify first.
Architecture — what's yours vs Sumsub's
Sumsub provides: the OIDC service (id.sumsub.com), the HMAC API
(api.sumsub.com), and the optional @sumsub/id-connect JS library that
mounts the button.
You write both halves of the integration:
Frontend (this stage) — page with the button. Generates PKCE, kicks
off the OIDC redirect to id.sumsub.com, receives ?code= in the
callback, POSTs { code, codeVerifier } to your own backend.
Backend (Stages 2-4) — HTTP endpoint that your frontend POSTs to.
Signs Sumsub API calls with your App Token + secret (which must NEVER
reach the browser), orchestrates the chain code → access_token → share token → reuse, and returns the materialised applicant.
The two halves are coupled by one route name — POST /api/sumsub/id-connect/exchange
in the examples; rename to fit your routing. Reference pair (matched):
examples/oidc-button.html (frontend) +
examples/express-callback.js (backend).
The backend is a thin orchestrator (~180 lines of Node/Express); port it to
your stack of choice — the wire format is identical regardless of language.
⚠️ onSuccess is not a verification signal. It only confirms the user
finished the OIDC consent step and Sumsub issued an authorization code.
The actual verification verdict comes from Stage 4 —
applicant.review.reviewStatus in the /reuse response (immediate, if
your recipient level runs no additional checks) or the applicantReviewed
webhook (authoritative, for any level that runs post-reuse checks).
Never grant access or unlock features based on onSuccess firing.
Three variants — use Method 1 (createButton) by default; the others
exist for design-system or no-bundler scenarios.
Method 1 — pre-built button via @sumsub/id-connect (recommended)
import { createButton } from'@sumsub/id-connect';
// PKCE helpers (S256 — full versions in examples/oidc-button.html).constb64url = (buf) => btoa(String.fromCharCode(...newUint8Array(buf)))
.replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
constsha256 = (s) => crypto.subtle.digest('SHA-256', newTextEncoder().encode(s));
// Generate the PKCE pair yourself, store the verifier under YOUR key — Stage 2// on the backend needs that verifier to exchange the code for an access token.const verifier = b64url(crypto.getRandomValues(newUint8Array(32)));
const challenge = b64url(awaitsha256(verifier));
sessionStorage.setItem('myapp.pkce.verifier', verifier);
createButton({
clientId: '<your-client-id>',
permissions: ['openid', 'share', 'name'],
container: document.getElementById('button-container'),
codeChallenge: challenge, // library uses YOUR challenge — skips its own PKCE genloginHint: 'user@example.com', // optional, prefills the email fieldonSuccess: async ({ code, state }) => {
const v = sessionStorage.getItem('myapp.pkce.verifier');
awaitfetch('/api/sumsub/id-connect/exchange', {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ code, codeVerifier: v, redirectUri: location.href }),
});
},
onError: (err) =>console.error('sumsub-id-connect error', err),
});
Why generate PKCE yourself: the Stage 2 token exchange needs the verifier.
If you let the library generate it, you depend on the library's internal
sessionStorage key (undocumented per minor version) to read it back in
onSuccess. Passing your own codeChallenge keeps the verifier under a key
you own. Same pattern works for Methods 2 and 3.
Direct navigation to the OIDC authorize endpoint, no Sumsub script on the
page. Reach for this when CSP forbids third-party scripts, you're in an
SSR-only environment, or you maintain a generic OIDC client across multiple
providers.
You generate the code_verifier (43–128 chars, URL-safe), derive
code_challenge = base64url(SHA256(verifier)), store the verifier
(sessionStorage), and forward it to your backend after the callback.
Sumsub only accepts code_challenge_method=S256 (plain is rejected) and
the redirect_uri must match the allowlist byte-for-byte.
Default ['openid', 'share', 'name']. Add email, profile, or
offline_access (refresh token) only when downstream logic actually reads
them — extra scopes trigger extra checks in the user-facing flow. Full table:
references/scopes-and-claims.md.
Stage 2 — Backend: code → access_token
Exchange the authorization code on the OIDC token endpoint. The code came from
the browser authorize flow, so its counterpart is the standard OIDC token
endpoint — authenticated with the OIDC client_secret (client_secret_basic),
not HMAC.
POST https://id.sumsub.com/api/snsId/oauth/token
Content-Type: application/x-www-form-urlencoded
Authorization: Basic base64(<client_id>:<client_secret>)
grant_type=authorization_code
&code=<the code your frontend got>
&redirect_uri=<exact-match URI from Stage 1 — byte-for-byte>
&code_verifier=<PKCE verifier matched to the code_challenge from Stage 1>
Response (24-hour access_token):
{"access_token":"snd-id-con-a-...","refresh_token":"snd-id-con-r-...",// only with `offline_access`"token_type":"Bearer","expires_in":86400,"id_token":"eyJhbGc..."// only with `openid` — RS256-signed}
Refresh later via grant_type: "refresh_token"; you cannot request more
scopes on refresh than were granted at consent time.
The client_secret stays server-side — never in the browser bundle. The
exchange is client_secret_basic / client_secret_post; do not HMAC-sign
it. (The App-Token + HMAC auth is still used in Stage 3a/4 for the share
token and reuse calls.)
Gotchas
Invalid code 401 has three common causes: PKCE mismatch (verifier
doesn't hash to the challenge sent at authorize), code already used
(single-use; refreshing the callback page double-fires), or code expired
(short TTL — exchange immediately).
redirect_uri must match Stage 1 byte-for-byte — trailing slash, casing,
port and query all count, or the exchange fails.
id_token validation — use a mature library (jose, pyjwt, jjwt)
against the jwks_uri from .well-known/openid-configuration. Never trust
unverified JWT contents.
Mint a share token scoped to a recipient (forClientId). Always implement
the consent fallback (Stage 3b) — sharingAllowed: false is returned
whenever the user hasn't yet authorised sharing with this specific
forClientId. In the common self-recipient case both consents are usually
granted in one click on the Stage 1 consent screen, but production code that
only handles sharingAllowed: true breaks the first time a user re-enters
the flow or a recipient configuration differs.
Stage 3a — mint share token
POST https://api.sumsub.com/resources/accessTokens/sumsubIdShareToken
{
"sumsubIdConnectToken": "<access_token from Stage 2>",
"forClientId": "<recipient clientId>",
"ttlInSecs": 1800
}
forClientId:
Self-recipient (common case): your own workspace clientId, visible in the
Dashboard top-left.
Third-party recipient: the partner's clientId (they must be pre-registered
as a partner in the Dashboard).
Response:
{"token":"_act-snsId-...","forClientId":"<echoed>","sharingAllowed":true// or false → continue to Stage 3b}
Stage 3b — partner-consent shareLink
If sharingAllowed: false, mint a consent link and redirect the user:
POST https://api.sumsub.com/resources/snsId/oauth/shareLink
Authorization: Bearer <access_token from Stage 2>
X-App-Token + X-App-Access-Ts + X-App-Access-Sig
{
"redirectUri": "<your shareLink callback URL — must be in the allowlist>",
"forClientId": "<same recipient clientId>",
"displayMode": "page",
"state": "<csrf-or-correlation-id>"
}
Response: { "link": "https://id.sumsub.com/share/<id>" } — expires in 5
minutes.
Persist the access_token server-side keyed by state (in-memory Map is OK
for demos; use Redis / encrypted cookie / session table for prod). Redirect
the user to the link. After consent, Sumsub redirects back to redirectUri
as ?token=<JWT> — a signed RS256 JWT whose payload carries state
(alongside sharingAllowed: true and forClientId).
⚠️ state is inside the JWT payload, not a top-level ?state= query
param. Decode the token JWT to read state back (verify its signature
against the jwks_uri first), then look up the saved
access_token by that state. Re-call Stage 3a — the share token now
returns sharingAllowed: true. Decoded payload shape:
{ iss, sub, aud, iat, exp, sharingAllowed, state, forClientId }.
Full reference implementation:
examples/express-callback.js (in-memory
pendingShare Map keyed by state, /share-complete handler).
Stage 4 — Materialise the applicant
With a usable share token, create the applicant in your workspace. Always
preview first.
Preview (no side effects)
GET https://api.sumsub.com/resources/api/reusableIdentity/reuse/preview
?shareToken=<token>
&levelName=<your-level>
&userId=<externalUserId>
Returns the same ApplicantPublicDto shape that /reuse would create — use
it to surface compatibility errors before committing.
Commit (creates the applicant)
POST https://api.sumsub.com/resources/api/reusableIdentity/reuse
?shareToken=<token>
&levelName=<your-level>
&userId=<externalUserId>
userId is the externalUserId Sumsub stores on the applicant — stable
per real user, opaque to the user, tied to your auth system. Same rules as
WebSDK.
Reuse error codes
All 400 responses include errorCode (integer) and errorName (kebab-case)
suitable for code branching. 401 is generic token validity — no errorCode,
just description.
HTTP / errorCode
name
Cause
Action
401 / —
Token is invalid
Share token expired (TTL exceeded), already consumed, or malformed
Re-mint via Stage 3a — call /sumsubIdShareToken again with the still-valid access_token
400 / 10501
not-in-partners-list
forClientId is not registered as a sharing partner of your workspace
Add the recipient as a partner in the Dashboard (Sumsub UI only — no public API)
400 / 10502
invalid-partner-id
The partner ID extracted from the share token is invalid
Re-check forClientId; re-mint share token against a real partner
400 / 10503
invalid-share-token
Share token is malformed or expired
Re-mint via Stage 3a
400 / 10504
non-suitable-share-token
Share token is not suitable for reuse at the given levelName (scope mismatch)
Re-mint share token with matching scope, retry against the same level
400 / 10505
reusable-kyc-disabled
Reusable KYC is disabled for this workspace
Contact Sumsub support to enable Reusable KYC for your workspace
400 / 10506
reusable-kyc-not-reusable
Generic fallback — donor doesn't meet reuse eligibility and no more specific reason matched
Inspect the donor in the Dashboard; pick a different donor or fall back to the WebSDK
400 / 10507
reusable-kyc-not-approved-applicant
Donor applicant is not in an approved state (pending / rejected / on-hold)
Wait for donor's KYC to be approved; use a donor with approved status
400 / 10508
reusable-kyc-not-active-applicant
Donor applicant is inactive (deactivated / blocked)
Use a different donor — reactivation is Sumsub-side
400 / 10509
reusable-kyc-not-kyc-moderation-type
Donor's source moderation type is not suitable for reuse
Donor needs standard KYC moderation; specialised flows aren't reusable
400 / 10510
reusable-kyc-not-selfie-or-identity-doc
Required selfie or identity document is missing on donor
Pick a level without that doc-set, or have donor re-verify
400 / 10511
reusable-kyc-not-selfie-liveness
Recipient level requires liveness; donor's selfie wasn't captured with liveness
Use a level without videoRequired: passiveLiveness on SELFIE, or have donor re-verify with liveness
400 / 10512
reusable-kyc-not-req-doc-overlap
Required document types don't overlap between donor and recipient levels
Pick a recipient level whose required docs are a subset of donor's
400 / 10513
reusable-kyc-not-compatible-doc-type
Recipient level requires document types the donor doesn't carry
Use a less strict level, or fall back to the WebSDK for full capture
400 / 10514
reusable-kyc-not-actual-poi-date
Donor's Proof of Identity is outdated and not valid for reuse
Donor must re-submit fresh POI, or relax recipient level's POI freshness window
400 / 10515
reusable-kyc-not-actual-poa-date
Donor's Proof of Address is outdated and not valid for reuse
Donor must re-submit fresh POA, or relax recipient level's POA freshness window
400 / 10516
reusable-kyc-not-acceptable-age
Donor doesn't meet the age criteria of the recipient level
No recovery — different user required
400 / 10517
reusable-kyc-incompatible-capture-settings
Capture settings (file upload vs live camera, etc.) mismatch between donor and recipient
Align recipient level's captureParams with what donor used, or have donor re-capture
400 / 10518
reusable-kyc-email-mismatch
Donor's email doesn't match the email already on the recipient applicant
Resolve duplicate-applicant collision — different externalUserId, or align emails
400 / 10519
reusable-kyc-phone-mismatch
Donor's phone doesn't match the phone already on the recipient applicant
Same as 10518 — resolve collision
400 / 10521
reusable-kyc-inactive-sumsub-id-account
Donor Sumsub ID account has no stored documents (email-only, KYC never completed)
Donor must complete full KYC on id.sumsub.com first; for testing, use a Sumsub-provided verified test account
After the applicant is materialised, your applicantReviewed webhook is the
authoritative signal for verification outcome — wire it up the same way as
for the WebSDK. See
sumsub-integrate-websdk for the
webhook material and
sumsub-manage-webhooks for the
sandbox webhook subscription setup.
Going-live checklist
When the user says "we're ready for prod":
Sumsub support has enabled Sumsub ID Connect for the productionclientId (separate from sandbox).
Production redirectUris (both authorize and shareLink callbacks) are
in the Dashboard allowlist on the prod workspace.
Backend token-exchange endpoint is auth-gated (only the authenticated
user can exchange a code minted for them).
id_token signature is verified against the prod JWKS.
externalUserId is stable per real user (not email, not display name).
/reuse/preview is called before /reuse so compatibility errors
surface as UX, not 4xx noise.
Stage 3b shareLink flow is implemented and tested — don't ship code
that only handles sharingAllowed: true.
In-memory state used for the shareLink callback is replaced with a
real session store (Redis / encrypted cookie / DB).
App Token + secret + OIDC client_secret are in the prod secret
store, not committed and not in browser bundles.
Refresh-token storage (if used) is server-side only, encrypted at
rest, single-tenant.
