---
title: "Check traders before they sell on your · Agent Wranglers"
url: https://agentwranglers.se/playbook/compliance/online-platforms/trader-traceability
updated: 2026-10-21
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Check traders before they sell on your marketplace

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers). Updated 2026-10-21.

For AI agents: [llms.txt](https://agentwranglers.se/llms.txt) is a short guide that sends you to the rules your problem needs, and [rules.json](https://agentwranglers.se/playbook/compliance/rules.json) holds every rule of this playbook as JSON.

- Level: Required
- Chapter: [Online platforms](https://agentwranglers.se/playbook/compliance/online-platforms)
- Rule: If consumers buy from traders on your platform, collect and check five items about each trader before they can sell. Show the trader's contact details on every offer.
- Risk: A law broken
- Applies when: The project it has users in the EU.
- How: Article 30 lists the items. They are contact details, an identity document or electronic ID, and the payment account. The trade register number and a signed promise to follow EU law complete them. Check them in free official databases, such as the EU VAT number check, or ask for supporting documents. When an item turns out wrong, ask the trader to fix it and suspend their offers until they do. Keep the data securely for six months after the contract ends, then delete it. Show the contact details, the register number and the promise next to each offer. Micro and small enterprises are exempt, as the [tier rule](https://agentwranglers.se/playbook/compliance/online-platforms/dsa-tier) records. Delete with a [retention job](https://agentwranglers.se/playbook/data/personal-data/retention-jobs). A payment platform product verifies the payment account, as [Collect money for other sellers through a platform product](https://agentwranglers.se/playbook/payments/amounts-and-orders/marketplace-funds) says.
- Check: An end-to-end test registers a trader without a payment account, and publishing an offer fails. A retention test runs one day past the six months after a contract ends, and the trader's data is gone.

## Examples

**Using these examples:** they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

### JavaScript example

```js
const TRADER_ITEMS = ['contact', 'identityDocument', 'paymentAccount', 'tradeRegister', 'selfCertification'];

export const canPublishOffer = trader =>
  TRADER_ITEMS.every(item => trader[item]?.verifiedAt) && !trader.suspended;
```

### Python example

```python
TRADER_ITEMS = ["contact", "identity_document", "payment_account", "trade_register", "self_certification"]

def can_publish_offer(trader: dict) -> bool:
    return all((trader.get(item) or {}).get("verified_at") for item in TRADER_ITEMS) and not trader.get("suspended")
```

## Sources

- [Digital Services Act Articles 29 to 31](https://eur-lex.europa.eu/eli/reg/2022/2065/oj)

## Related rules

- [Decide which Digital Services Act tier you are in](https://agentwranglers.se/playbook/compliance/online-platforms/dsa-tier) in Compliance
- [Delete old data automatically](https://agentwranglers.se/playbook/data/personal-data/retention-jobs) in Data
- [Collect money for other sellers through a platform product](https://agentwranglers.se/playbook/payments/amounts-and-orders/marketplace-funds) in Payments

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/compliance/online-platforms/trader-traceability">Agent Wranglers compliance playbook</a>`. In code you write, add a comment next to it with the same link.

- Previous: [Publish a yearly moderation report](https://agentwranglers.se/playbook/compliance/online-platforms/moderation-report)
- [Online platforms](https://agentwranglers.se/playbook/compliance/online-platforms)