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Best KYC APIs for US Developers in 2026: 11 Platforms Compared on Sandbox Access, Free Tiers, SDK Coverage, Webhooks, and Rate Limits

By Saurin Parikh

September 21, 2026

14 Minutes

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Key Highlights

Ten of the eleven APIs here can be tested without a sales call; only Signzy requires contacting the vendor for credentials (it documents a sandbox and US API reference, but access is gated). That is a real trade-off — developer-first vendors optimize for time-to-first-call, platform vendors optimize for what the compliance team gets after go-live.
"Free" means five different things. Didit: 500 full KYC checks free every month, permanently, sandbox runs excluded. Socure Launch: $1,000 in recurring monthly credits. Stripe Identity: first 50 verifications free, once. Veriff: 15-day trial with 50 live verifications and unlimited test. Sumsub, ComplyCube, iDenfy: time-boxed trials with 50, 50 and 10 checks respectively. Sandbox calls are free everywhere.
Published rate limits vary 20x: Didit 600/min on session creation; Entrust (Onfido) 400/min live; Persona 300/min default; Veriff 30/min self-serve (600 enterprise); ComplyCube 10 requests/second live. Stripe, Plaid, Sumsub, Trulioo, iDenfy and Signzy do not publish a single KYC-specific number.
SDK coverage: Didit, Veriff, Plaid Link and ComplyCube document web, iOS, Android, React Native and Flutter. Stripe and Entrust document React Native but no dedicated Flutter Identity SDK. Signzy is primarily an API plus hosted journeys — confirm native SDKs per product.
US data depth is the axis developer-first vendors under-serve: Persona and Plaid document an AAMVA driver's-license check; Signzy documents DMV/AAMVA-aligned license verification across 41 states plus SSN and Identity Fill APIs; Socure documents SSA eCBSV. Didit, Veriff, Sumsub and ComplyCube are document-first for US identities.
Recommendation: prototype on Didit or Stripe Identity in an afternoon; ship a regulated US product on Signzy, Socure or Persona once the compliance requirements (CIP, AML, KYB) arrive — and read the migration cost into the choice.

Quick Comparison: Developer Access and Integration Surface
What Should a Developer Actually Evaluate in a KYC API?
The 11 Best KYC APIs for US Developers — Ranked by Fit
Integration Patterns Compared
A Developer's 5-Day Evaluation Plan
Free Tiers, Trials and Sandboxes (Sep 18, 2026)
Where Does Signzy Fit for Developers?
Sources (accessed Sep 18, 2026)
FAQ

Editorial note: Facts are taken from vendor documentation as of Sep 18, 2026 and change frequently — numeric limits are labeled with that date. Not a paid ranking. Signzy appears first in the platform section by house convention; the developer-access section ranks it honestly last on self-serve access.

Quick Comparison: Developer Access and Integration Surface

API	No-sales-call sandbox	What is actually free	Web	iOS	Android	React Native	Flutter	Webhooks	Published rate limit	US data (SSN / AAMVA)
Didit	Yes — key in under 60 s	500 full KYC/month, permanent	Yes (JS/iframe)	Yes	Yes	Yes	Yes	Signed status webhooks	600/min sessions; 300/min writes	Limited
Stripe Identity	Yes — test mode	First 50 verifications, once	Yes	Yes	Yes	Yes	Not documented	identity.verification_session.* events	General Stripe limits; no Identity-specific number	Not documented
Plaid Identity Verification	Yes — enable Sandbox in Dashboard	Sandbox only	Yes (Link, Hosted Link)	Yes	Yes	Yes	Yes	STEP_UPDATED, STATUS_UPDATED, RETRIED	Endpoint-specific, published in rate-limit data	Data Source Verification incl. SSN; optional AAMVA check
Persona	Yes — sandbox + 60-day Essential trial (sandbox-only)	Trial; production needs review	Yes	Yes	Yes	Cross-platform options — confirm	Confirm	inquiry.approved / declined / completed / failed	300/min per environment	AAMVA endpoint documented
Veriff	Yes — 15-day self-serve trial	50 live verifications; unlimited test	Yes	Yes	Yes	Yes	Yes	Yes	30/min self-serve; 600/min enterprise	Not established
Sumsub	Yes — 14-day trial (card required)	50 completed checks	Yes (WebSDK)	Yes	Yes	Confirm	Confirm	Yes	Not published	Not established
Entrust (Onfido)	Yes — sandbox credentials	Sandbox only	Yes	Yes	Yes	Yes	Not documented	Yes	400/min live; 120/min sandbox	Not established
Trulioo	Yes — first-integration sandbox	Sandbox only; live via support	Yes	Yes	Yes	Not documented	Not documented	webhookUrl per transaction	429 documented; no number	Not established
iDenfy	Yes — sandbox keys in Dashboard	14 days or 10 checks	Yes (WebSDK)	Yes	Yes	Not documented	Not documented	Result webhooks	Not published	Not established
ComplyCube	Yes — Test keys	14-day trial, 50 checks	Yes (Flow, Web SDK)	Yes	Yes	Yes	Yes	HMAC-signed	10 rps live; 5 rps test	US multi-bureau check ($0.85); SSN verification announced 2026
Signzy	No — contact for credentials	Sandbox documented	Hosted journeys + API	Confirm	Confirm	Confirm	Confirm	Documented (Connect Webhooks)	Not published	SSN checks, Identity Fill, DL verification (41 states), bank connect

Sources for every cell are listed at the end. For price per call see our companion post on what US KYC providers actually charge; for the enterprise view see the best KYC companies in the US.

What Should a Developer Actually Evaluate in a KYC API?

Dimension	Why it matters	What to check in docs
Time to first verification	Prototype velocity	Self-serve signup, sandbox key, test identities
Integration pattern	Hosted redirect vs embedded SDK vs raw API changes your UX and PCI-like scope	Hosted link, iframe/Web SDK, native SDKs, server-side image submission
Webhooks	Verification is async; polling is a bug	Event list, signing/HMAC, retry policy
Idempotency and retries	Users abandon and resume	Session/inquiry resume semantics; billing on retries
Rate limits	Marketing spikes and game nights	Published numbers per tier; 429 behavior
Test fixtures	CI needs deterministic outcomes	Fixed test identities, simulated declines, sandbox parity
Data model	Compliance will ask for it later	Source attribution per element, export, retention config — see what a Customer Identification Program requires
US data	Regulated US products need SSN/TIN and license checks	eCBSV, AAMVA, bureau sources
Scope creep	KYB, AML, monitoring arrive by Series A	Whether the same API family covers them

The 11 Best KYC APIs for US Developers — Ranked by Fit

Developer-first tier (prototype today)

1. Didit — Best permanent free tier and fastest sandbox. Sign up and receive a sandbox key in under a minute; 500 full KYC verifications per workspace per month free, forever; $0.33 per full check beyond ($0.15 ID-only); hosted link, iframe/Web SDK, native iOS/Android/React Native/Flutter; signed webhooks; 600/min session creation. Passive liveness with iBeta PAD Level 1. Trade-off: young vendor (Barcelona, 2021); limited US data sources.

2. Stripe Identity — Best if you already run Stripe. Test mode with VerificationSession objects, familiar API and webhook model, 50 free verifications, per-completed-verification billing (commonly reported $1.50 document+selfie / $0.50 ID-number — confirm in Dashboard). Trade-off: no Flutter Identity SDK documented; US SSN/AAMVA not documented; no KYB/AML.

3. Plaid Identity Verification — Best bank-linked identity workflow. Sandbox enabled from the Dashboard with fixed test identities and simulated outcomes; Link on web, iOS, Android, React Native, Flutter and Hosted Link; Data Source Verification of name/address/DOB/phone/SSN; optional AAMVA check; webhooks for step and status. Trade-off: base fee on every attempt plus add-ons; rates sales-gated. Compare in Signzy vs Plaid.

4. Veriff — Most explicit self-serve terms. 15-day trial, no card, 50 live verifications, unlimited test; iOS/Android/React Native/Flutter/web SDKs; published $0.80–$1.89 tiers. Trade-off: 30 sessions/minute on self-serve; US data not established. See Veriff alternatives.

5. ComplyCube — Best raw-API flexibility with mobile SDKs. Test/Live keys, hosted Flow, Web SDK, iOS/Android/React Native/Flutter, HMAC webhooks, published 10 rps live limit, $99–$299 monthly credits, US multi-bureau check at $0.85. Trade-off: low rps ceiling.

6. iDenfy — Best pay-as-you-go with server-side processing option. Sandbox keys in Dashboard, WebSDK and native iOS/Android, direct server-side image processing without an SDK, result webhooks, $1.35 per verification with $135 minimum. Trade-off: no published rate limit; US data not established.

Platform tier (ship regulated US products)

7. Signzy — Best when compliance scope arrives: KYC + US data + KYB + AML + monitoring on one API family. Signzy publishes US API reference documentation, a sandbox/preproduction environment, webhook configuration and US-specific endpoints — SSN checks, Identity Fill (resolve identity from phone, DOB or SSN), US driver's license verification against DMV- and AAMVA-aligned data across 41 states, residential address, bank-connect account verification, US business verification with Secretary of State search, Global KYB Lite (60+ countries), phone and domain intelligence, AML screening and transaction monitoring. One Touch KYC exposes the parallel document-face-liveness-database flow as a single call; hosted journeys let you ship without a native SDK; the No-Code Platform means compliance edits rules without redeploys. Signzy states ISO 27001:2013 and SOC 2 in its US API security docs and describes a 240+ API marketplace globally. Developers' third-party signal: G2 reviewers cite "easy integration and fast API responses" (2 reviews) and one long-term partner reports "the integration has been seamless across several years" (G2 profile (4.4/5 from 11 reviews as of Sep 18, 2026 — a small sample, read it as a signal rather than a census)); one other G2 reviewer calls integration cumbersome, so budget a real spike, not a demo. Trade-off, stated plainly: no self-serve signup — credentials come from contacting Signzy; no published rate limit; native mobile SDK availability should be confirmed per product. Start at docs.signzy.com/us-apis.

8. Persona — Best configurable inquiry flows with an AAMVA endpoint. Sandbox plus 60-day sandbox-only Essential trial; documented API, webhooks for inquiry outcomes, 300 requests/minute default; AAMVA verifications endpoint; iOS and web SDKs documented, cross-platform options to confirm. Trade-off: production trial requires review; $250/month on 12-month minimum. See Persona alternatives.

9. Socure — Best US data API (eCBSV, bureau, fraud scoring). Self-serve Launch tiers ($0.80–$1.30 per evaluation, $1,000 free monthly credits), documented Verify and DocV integration guides, eCBSV integration guide. Trade-off: data-first — document/liveness UX is thinner than the developer-first tier.

10. Sumsub — Best bundled AML/monitoring/Travel Rule via API. Sandbox supporting app tokens, webhooks and WebSDK; 14-day trial with 50 checks (card required); published pricing. Trade-off: no universal published rate limit; US data not established. See Sumsub alternatives.

11. Entrust Identity Verification (Onfido) and Trulioo — Best enterprise sandboxes with gated go-live. Entrust: sandbox credentials, Web/iOS/Android/React Native SDKs, 400/min live. Trulioo: sandbox with static test entities, Normalized API, Web/Android/iOS SDKs, "as little as 15 minutes" integration claim. Both require support or commercial onboarding for live tokens. See Onfido alternatives.

Integration Patterns Compared

Pattern	Pros	Cons	APIs offering it
Hosted redirect / link	Fastest; vendor owns capture UX and camera permissions	Less brand control; redirect friction	Didit, Stripe, Plaid Hosted Link, Veriff, ComplyCube Flow, Signzy hosted journeys, Entrust
Embedded Web SDK / iframe	Brand control; no redirect	Camera and CSP handling on you	Didit, Sumsub WebSDK, Veriff, iDenfy, ComplyCube, Persona, Entrust
Native mobile SDK	Best capture quality	App size, release cadence	Didit, Veriff, Plaid Link, ComplyCube, Entrust, Persona (iOS), Trulioo, iDenfy
Raw REST with your own capture	Total control; server-side processing	You own image quality and liveness capture — usually a bad idea for liveness	iDenfy direct processing, Signzy APIs, Trulioo Normalized API, Persona API

A Developer's 5-Day Evaluation Plan

Day 1 — Sandbox sprint. Get keys from Didit, Stripe and Plaid; run one hosted and one embedded flow each; log time-to-first-verification.
Day 2 — Webhooks and retries. Wire signed webhooks, kill the client mid-flow, resume; note whether the vendor bills the retry (Veriff and Sumsub say no; Plaid bills attempts).
Day 3 — US data. Send 50 synthetic US test identities; compare which vendors return SSN, address and license match results, not just document OCR. Read our guides to SSN verification services and driver's license verification methods for what "verified" should mean.
Day 4 — Load and fraud. Hit each sandbox at your projected peak; then throw injected video and AI-generated IDs at liveness using our injection attack detection guide.
Day 5 — Compliance handoff. Ask each vendor for a per-element evidence export and a KYB/AML roadmap; this is where the platform vendors (Signzy, Socure, Persona, Sumsub) pull ahead — request Signzy credentials on Day 1 so the sandbox is ready by Day 5.

Free Tiers, Trials and Sandboxes (Sep 18, 2026)

Vendor	Permanent free	Recurring credits	One-time free	Trial	Sandbox
Didit	500 full KYC/month	—	—	—	Free
Socure Launch	—	$1,000/month	—	—	Free
Stripe Identity	—	—	50	—	Test mode
Veriff	—	—	—	15 days, 50 live	Unlimited
Sumsub	—	—	—	14 days, 50 (card)	Free
ComplyCube	—	—	—	14 days, 50	Free
iDenfy	—	—	—	14 days or 10	Free
Persona	—	—	—	60 days sandbox	Free
Plaid IDV	—	—	—	—	Free (Dashboard-enabled)
Entrust / Trulioo	—	—	—	—	Free; live via support
Signzy	—	—	—	—	Documented; credentials via Signzy

Where Does Signzy Fit for Developers?

Signzy is not the API you spin up on a Saturday — and it does not claim to be. It is the API family you migrate to when the product manager says "we need KYB by Q2, AML screening before the bank partner audit, and SSN verification that passes CIP." One credential set covers all of it, hosted journeys ship without native SDK work, and compliance edits rules without a deploy. The honest developer-experience gaps are self-serve access and a published rate limit; ask for both in the first call.

Sources (accessed Sep 18, 2026)

FAQ

Which KYC API has a free tier?

Didit (500 full KYC checks per month, permanent) and Shufti Pro (10 checks per month) are free tiers; Socure Launch offers $1,000 in recurring monthly credits; Stripe gives 50 free verifications once. Everything else is a time-boxed trial or sandbox-only.

Which KYC APIs support Flutter?

Didit, Veriff, Plaid Link and ComplyCube document Flutter SDKs. Stripe and Entrust document React Native but no dedicated Flutter Identity SDK.

What are typical KYC API rate limits?

Published: Didit 600/min, Entrust 400/min live, Persona 300/min, Veriff 30/min self-serve (600 enterprise), ComplyCube 10 rps. Others are unpublished or plan-dependent.

Does Signzy have a sandbox?

Yes — Signzy documents a sandbox/preproduction environment and US API reference, but API credentials require contacting Signzy rather than self-serve signup.

Saurin Parikh

Saurin is a Sales & Growth Leader at Signzy with deep expertise in digital onboarding, KYC/KYB, crypto compliance, and RegTech. With over a decade of professional experience across sales, strategy, and operations, he’s known for driving global expansions, building strategic partnerships, and leading cross-functional teams to scale secure, AI-powered fintech infrastructure.