Trello API tokens

Connect Trello with an API token created for the Sim deployment's API key. The token acts as the Trello member who authorized it and can access that member's boards.

Prerequisites

In Sim, you need workspace write access and permission to manage integrations.

You need a Trello account that has access to the boards your workflows will read and write. For production workflows, create a dedicated bot Trello account (e.g. sim-bot@yourcompany.com), invite it to the relevant boards, and mint the token while logged in as that account — the credential then survives any individual employee leaving.

Generating the API token

Trello doesn't have a token-creation settings page. Tokens are minted by visiting an authorize URL in the browser while logged in to the Trello account that should own the token:

https://trello.com/1/authorize?expiration=never&scope=read,write&response_type=token&name=Sim&key=<SIM_TRELLO_API_KEY>

The key parameter must be the Trello API key of the Sim deployment:

• Sim's hosted cloud — contact Sim support for the authorize link with the deployment's key already filled in. Do not substitute your own key.
• Self-hosted Sim — substitute the value of your deployment's TRELLO_API_KEY environment variable. Trello API keys are public-by-design identifiers (not secrets); yours is shown at trello.com/power-ups/admin under your Power-Up's API key page.

1. 1

   Log in to Trello as the account that should own the token (the bot account, for production)

2. 2

   Open the authorize URL above in the browser. Trello shows a consent page describing the access being granted

3. 3

   Click Allow. Trello displays the token on-screen — copy it

Newer Trello tokens start with ATTA; older ones are 64-character hex strings. Both work — Sim doesn't enforce a format.

Adding the API token to Sim

1. 1

   Open Integrations from your workspace sidebar

2. 2

   Search for "Trello" and open it, then click Add to Sim and choose Add API token

3. 3

   Paste the API token, and optionally set a display name and description

4. 4

   Click Add API token. Sim verifies the token by calling Trello's /1/members/me endpoint — if it fails, you'll see a specific error explaining what went wrong.

The token is encrypted before being stored.

Using the credential in workflows

Add a Trello block to your workflow. In the credential dropdown, select the saved Trello API token. Choose the operation and configure its inputs. The block calls Trello's API (api.trello.com) with the token, paired server-side with the deployment's API key. The credential acts as the Trello member that minted the token, with access to exactly the boards that member can see.

Verify access, rotate, or revoke

Run a read action against a board the issuing member can access, then test any required write. A read-only or short-lived token can pass connection validation and still fail later; use the scope and expiration in the authorize URL for the full action set documented here.

The member's current permissions determine board access. If a board becomes inaccessible, restore the member's access before retrying. If token creation is blocked for an Enterprise-managed account, ask the Trello Enterprise admin about its application restrictions.

To rotate, mint a replacement with the same deployment API key, update the saved credential in Sim, and verify the workflow. Then open https://trello.com/u/my/account as the token's owner and revoke the old Sim entry under Applications. Revoking a token prevents further API access. See Trello's authorization reference.