Marketplace Seller Onboarding with KYB

Marketplaces live and die by the quality of their supply side. Onboarding sellers fast is what grows the catalog — but onboarding the wrong sellers is what gets a platform fined, defrauded, or de-banked by its payment partner. Business sellers raise the stakes further: a seller that's a registered company means you're not just verifying a person, you're verifying an entity, identifying who owns it, screening it for sanctions, and checking its documents before money starts flowing to it. Done by hand, that's days of work per seller. Done as a registry lookup alone, it's a compliance gap waiting to be exploited.

Didit's Business Verification API turns marketplace seller onboarding into a single KYB session. Verify the company, identify and KYC every owner, screen the entity, and check the documents — all on the unified /v3/ API, for $2.00 per company. This guide walks through how to onboard business sellers properly without making it slow.

Key takeaways

• One session per seller. A single KYB session covers registry, UBO identification, owner KYC, entity AML, and document checks.
• $2.00 per company. The full verification is one flat price per seller entity, with no minimums — cost scales with seller volume.
• KYC every owner. Closed-loop KYB spawns a linked KYC session for each UBO, so you verify the humans behind the seller before payouts — unique to Didit.
• Catch the bad entities. Entity-level AML ($0.20) flags a sanctioned or adversely-reported seller company even when its officers look clean.
• Verify documents, don't just store them. KYB documents ($0.20 each) are read with OCR and tamper-checked.
• Built for scale. Per-feature statuses let you route resubmissions and reviews without failing the whole onboarding; webhooks keep your seller records in sync.

What seller KYB does

For a marketplace, a business seller is an entity you're about to pay. KYB answers the questions that protect those payouts: Is this a real, in-good-standing company? Who ultimately owns it? Is the entity or any owner on a sanctions list? Are its documents genuine? Didit's session model answers all four in one place via four features — kyb_registry, kyb_key_people, kyb_company_aml, and kyb_documents — and, with linked KYC switched on, verifies the actual identities of the owners too.

The result is a seller you can trust enough to pay: a verified company, a resolved ownership graph, screened entity and owners, and tamper-checked documents — produced from one session rather than five tools.

Why it matters

Marketplaces that handle payouts are increasingly treated as regulated money flows. Payment partners and acquirers demand seller due diligence; AML regimes require identifying and verifying beneficial owners of business counterparties; and the fraud reality is that bad sellers hide behind shell entities precisely because onboarding rarely looks past the registry line. A platform that pays out to an unverified, sanctioned, or fictitious seller entity carries the loss and the regulatory exposure.

The tension is speed. Sellers abandon onboarding that takes too long, so the verification has to be thorough and fast. The way to get both is to run every check in one session with precise per-feature routing — collect what's needed, verify it automatically, and only involve a human where a real risk signal appears.

Technical details

Seller onboarding starts with a KYB session on the unified /v3/ API, tied to your internal seller record via vendor_data.

curl -X POST https://verification.didit.me/v3/session/ \
  -H "x-api-key: $DIDIT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "workflow_id": "your_kyb_workflow_id",
    "vendor_data": "seller_44120",
    "callback": "https://yourmarketplace.com/sellers/kyb/callback"
  }'

The session result gives you everything needed to decide on a payout, including linked KYC on the owners:

{
  "session_id": "kyb_91ab30c4",
  "status": "APPROVED",
  "vendor_data": "seller_44120",
  "kyb_registry": { "status": "APPROVED", "company_status": "ACTIVE" },
  "kyb_company_aml": { "status": "APPROVED" },
  "kyb_documents": { "status": "APPROVED" },
  "kyb_key_people": {
    "status": "APPROVED",
    "ubos": [
      { "name": "Ana Ferreira", "ownership_percentage": 70.0,
        "linked_kyc": { "session_id": "kyc_aa10", "status": "APPROVED" } },
      { "name": "Bruno Costa", "ownership_percentage": 30.0,
        "linked_kyc": { "session_id": "kyc_aa11", "status": "APPROVED" } }
    ]
  }
}

Session statuses. NOT_STARTED, IN_PROGRESS, APPROVED, DECLINED, IN_REVIEW, RESUBMITTED, ABANDONED, EXPIRED.

Webhooks. Subscribe to status.updated and data.updated (session_kind: business) for the seller's verification, and the standard session webhooks for each owner's linked KYC. Use business.status.updated to track the seller entity's standing after onboarding.

Price. $2.00 per company. Disaggregated: company AML $0.20, KYB documents $0.20 each, Key People free, linked owner KYC at standard User Verification rates.

Onboarding flow for a marketplace

1. Seller starts onboarding. You create a KYB session keyed to your seller ID.
2. The company is verified. Registry confirms the entity is real and ACTIVE; documents are collected, OCR-read, and tamper-checked.
3. Owners are identified and verified. Key People resolves the UBOs, and a linked KYC session verifies each one — closing the loop between the entity and the humans.
4. Everyone is screened. Entity AML screens the company; AML on each owner's KYC screens the people.
5. You decide on payouts. An APPROVED session with verified owners and clean screening clears the seller for payouts; an IN_REVIEW or RESUB_REQUESTED feature routes precisely to the one thing that needs attention.

After onboarding, the seller becomes a managed entity you can keep ACTIVE, FLAGGED, or BLOCKED through the businesses API as their standing changes.

Use cases

• Product marketplaces onboarding merchant sellers verify the merchant entity and its owners before enabling settlement.
• Service and gig marketplaces with business providers run KYB on incorporated providers to satisfy payout-partner due diligence.
• Creator and commerce platforms paying out to business accounts confirm the entity and its beneficial owners are real and screened.
• B2B and wholesale marketplaces verify counterparty companies and their owners before extending trade terms or payouts.

How to integrate with Didit

1. Build the workflow. In the Business Console, create a KYB workflow with registry, company AML, documents, and key people enabled, plus linked KYC for UBOs.
2. Create the session. POST /v3/session/ with your KYB workflow_id and a vendor_data reference matching your seller ID.
3. Handle webhooks. Listen for the seller's status.updated / data.updated (session_kind: business) and each owner's linked KYC webhooks; gate payouts on the combined result.
4. Manage the seller. Use GET /v3/businesses/{vendor_data}/ and PATCH .../update-status/ to keep the seller ACTIVE, FLAGGED, or BLOCKED as their standing changes.

Because it's all on the unified /v3/ API, verifying the seller company, KYC-ing its owners, and monitoring it afterward are one continuous flow — one identity-and-fraud platform, end to end.

Frequently asked questions

How much does it cost to onboard a business seller?

$2.00 per company for the full KYB verification. Owner KYC sessions are billed at standard User Verification rates; company AML and KYB documents are $0.20 each if you buy them separately.

Do I have to verify the seller's owners, or just the company?

You can do both in one flow. Closed-loop KYB identifies the UBOs and spawns a linked KYC session for each — so you verify the humans behind the seller before paying out.

Will it catch a sanctioned seller company?

Yes. Entity-level AML (kyb_company_aml) screens the company itself, catching a designated firm even when its officers screen clean.

Is onboarding slow if it does all this?

No. Every check runs in one session, and per-feature statuses let you route a single resubmission or review without failing the whole onboarding — thorough and fast.

How do I keep a seller's standing up to date after onboarding?

The seller becomes a managed entity you can set to ACTIVE, FLAGGED, or BLOCKED through the businesses management API, with business.status.updated webhooks on every change.

Ready to get started?

Read the Business Verification overview in the docs, see how it fits the rest of the platform on the Business Verification product page, and check transparent per-call pricing on the pricing page. When you're ready, start free — 500 free KYC checks every month, and business verification at $2.00 per company.