Metronome vs Paid

Metronome

Metronome's API carries an Idempotency-Key on every POST, a public OpenAPI description of 142 operations, and agentic tokens whose writes wait for a person's approval. Prices for the Startup plan are public. Errors return only a message string, token scopes are set through support, and the status feed lists 13 incidents since 22 July 2026.

Paid

Paid suits a builder who wants usage metering, credits and invoicing behind one API, with restricted and customer-bound keys, OAuth on the MCP server and a free plan that needs no card. No status page, SLA figure, API changelog or rate-limit numbers were found, both advertised OpenAPI links returned 404, and card payments need the builder's own Stripe account.

Metronome

1. Send an Idempotency-Key header on every POST and reuse it on retry. A cached error is returned for the same key, so use a new key after fixing the cause
2. Give each usage event a stable transaction_id. Metronome ignores repeats for 34 days and accepts at most 100 events per /v1/ingest call
3. On 429 read X-Metronome-Rate-Limit-Type (client or customer) and back off. Unlisted endpoints default to 8 requests a second
4. With an agentic token, expect 403 AgenticMutationBlocked on writes. Post the original method, path and body to /v1/approval_requests and show the person the approval_url
5. Use a sandbox token for testing. The token alone decides whether a call reaches sandbox or production data

Paid

1. Call https://api.agentpaid.io/api/v2 with Authorization: Bearer <key>. A person creates the first key at app.paid.ai. No programmatic signup was found
2. Give every signal a stable idempotencyKey and resend the same key on retry. Signals without one are not deduplicated
3. Send at most 500 signals a request. A 429 rejects the whole batch, so wait for Retry-After and resend it all
4. Read the code field on a 429. CONCURRENCY_LIMIT_EXCEEDED carries no Retry-After and clears when an analytics query finishes
5. Install the Python SDK as paid-python, the name in its README and pyproject.toml. The quickstart's pip install paid names a package we could not check