Skip to main content
Requests to https://api.qfex.com select a contract with the api_version query parameter. A contract defines the request fields, validation, and response format. The date identifies a published contract; it does not select historical market data.

​
Select a version

For integrations that need a stable format, send an explicit date on every request. Requests without a date follow future contract changes automatically.
Keep the endpoint path unchanged. If a URL already has query parameters, append &api_version=2026-10-29. Authentication requirements are the same for every version. The Qfex-Api-Version response header identifies the selected contract, including when you omit the parameter or send latest.

​
Supported contracts

Only published dates are accepted. Empty, repeated, malformed, or unsupported api_version values return HTTP 400; the API does not round dates to a release.

​
Browse and try a contract

Use the top-level version dropdown to choose Latest or a published date, then open the API Reference tab. Latest follows the current public specification. A dated selection loads that contract’s specification and has its own reference URLs.
Selecting a documentation version does not add a version to your API requests. When using the playground or copying a request, explicitly set api_version to the date you are reading. Leaving it empty sends a request to latest.
The latest OpenAPI specification moves with new releases. Use a dated OpenAPI link from the table above for client generation against a specific contract. Your generated client must also send the date on its requests.

​
Upgrade an integration

  1. Read the API changelog and the target contract’s reference.
  2. Update your request construction and response parsing for the target contract.
  3. Test requests with the target api_version, including validation and error handling.
  4. Change the pinned date in your integration once those checks pass.
Versioning preserves the selected wire contract. Responses still reflect current market and account state, and requests run current business logic.

​
Scope

This parameter applies to the REST API on api.qfex.com. The Funding API on banker.qfex.com and the WebSocket API have separate interfaces and do not use this version selector. Health checks and dated contract metadata URLs are outside query-based contract selection.