REST API: get started

With the fynk REST API, you connect fynk to your own systems: create documents from templates or PDFs, fill dynamic fields and metadata, add signatories, start signing and download the signed PDF.

Available on Business and Pro · Owner

Before you start

• Create at least one party under Account settings → My Parties.

• Create at least one template, if you want to create documents from templates.

Create an API token

1. Go to Account settings → API integrations and click Configure on the fynk API tile.

2. Under API Tokens, click Create Token.

3. In Create New API Token, enter a Token Name and select one or more Roles: Document Reader, Document Manager, Document Deleter, Template Reader, Template Manager, Tag Manager, Metadata Manager. The roles decide what the token can do.

4. Optionally, set an Expiry Date. The token expires automatically on that date. Leave it blank for no expiry.

5. Copy the token and store it securely. You won't see it again.

The API Tokens list shows each token's name, creation date, expiry date and roles.

Make your first request

Send the token in the header of every request:

Authorization: Bearer <your token>Accept: application/json

Test it with GET https://app.fynk.com/v1/api/me. You should get a 200 response with details about your token.

What you can do with the API

• Create documents from a template or from a PDF

• List, read and update documents

• Fill dynamic fields and metadata

• Add, change and remove parties and signatories

• Move documents to review or signing

• Download the latest PDF

• Attach files and link documents

API reference

Use the API reference in this help center for endpoints, parameters and examples. It is synced from fynk’s API schema. The reference is also available at app.fynk.com/v1/docs.

For signature-type values, including aes_eid, see Update document. AES (eID) uses sequential signing; see Signature types for the workflow.

Prepare signature positions before automating

Adding a signatory and placing their signature block are separate steps. The published API does not expose a dedicated endpoint for positioning signature blocks on an uploaded PDF. For a repeatable workflow, create documents from a template with blocks already placed. For one-off PDFs, place the blocks in fynk before moving the document to signing.

API version

On the fynk API page, under API Version Settings, choose the Default API Version, for example 2025-06-06. fynk uses this version for every API request that doesn't send a fynk-Api-Version header. Changing the default may affect existing integrations that don't send the header.

API Version Changelog lists the changes per version. The API Documentation button opens the API reference.

Good to know

• Tokens created during your trial stop working after the trial unless you upgrade.

• Each token gets roles (e.g. Document Reader, Document Manager, Template Reader) that decide what it can do, and an optional expiry date. Tokens can't be limited to certain teams.

• The API is rate-limited per minute. If you exceed the limit, you get a 429 response with a Retry-After header.

• Pin an API version per request with the fynk-Api-Version header. Without the header, the default API version is used. Breaking changes always come with a new version.

• Parties and signatories can only be changed while a document is in draft or review.

• Signers can't be redirected to your website after signing. They return to the tab where they opened the document.

• To react to events in fynk instead of polling, use webhooks. See Webhooks.

Related articles

• Webhooks

• Integrations overview

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