Argyle vs Check

Argyle

Graded on the REST API. One OpenAPI file covers 91 operations, llms.txt indexes Markdown docs, and a Sandbox with sample users comes with a Console sign-up. Every payroll connection needs the worker to sign in through Link. No prices are published, no idempotency keys were found, and API keys carry no per-key scopes.

Check

Graded as embedded payroll through a partner API key, not access to an existing employer's payroll account. The API has idempotency keys on writes, a required preview before approval and queryable request logs. No price is public, a sandbox key comes through Check's sales team, and one API key carries the whole partner account.

Argyle

1. Send HTTP Basic auth with api_key_id as the username and api_key_secret as the password. Sandbox keys fail with 401 on Production and the reverse
2. Create the user with POST /v2/users and an external_id, then look it up by external_id before retrying. No idempotency key was found
3. Do not read data straight after an account connects. Wait for the account and data webhooks, or for the verification status, before fetching records
4. Follow the full URL in next when paging. Do not build cursor values or fetch pages in parallel. limit defaults to 10 and stops at 200
5. Stay under 50 requests a second. On 429, queue the request and retry later, not at once
6. Treat DELETE /v2/users/{id} as permanent. It removes every resource tied to that user, with no confirmation step

Check

1. Use https://sandbox.checkhq.com with the sandbox key and https://api.checkhq.com with the production key. A key is not valid across environments
2. Preview a payroll before approving it, then pass preview_started_at to POST /payrolls/{id}/approve so a stale preview fails with 409
3. Send X-Idempotency-Key on every write. Keys expire after 24 hours, so list the resource before retrying later than that
4. On 429 wait for Retry-After. The limit is 10 requests a second in sandbox and for partners paying fewer than 1,000 payees a month, with 100 concurrent requests
5. Connect the MCP server with ?read_only=true or X-MCP-Readonly: true unless writes are intended. In production, approving a payroll moves money