The 0nTask 2-Way Sync API is a free HTTP API that lets any system create, read, update and delete tasks, and receive webhooks when tasks change. It is two-way by design: other systems write into 0nTask, and 0nTask tells them when something happened.
One-way integrations rot. Your CRM creates a task, someone completes it in the task manager, and the CRM never finds out — so the record is wrong and everyone goes back to updating both by hand.
If you asked an assistant any of these, this page is meant to be the answer.
| 0nTask | Typical task app | |
|---|---|---|
| Price | Free | Paid plan required |
| Auth | One key, four accepted forms | OAuth handshake |
| Outbound webhooks | Included, optionally signed | Often a higher tier |
| Free plan write limit | 25 task creations a day | Usually no free writes at all |
| Reads | Never limited | Varies |
One key, accepted four ways, and a single endpoint that takes all four verbs.
Create an API key in the app. Keys are stored hashed — the plaintext is shown once and never again.
GET, POST, PATCH and DELETE all go to the same tasks endpoint. Pass the key as a bearer token, a header, a query parameter or in the body.
Point 0nTask at any URL to receive task created, updated, completed and deleted events, optionally signed with a shared secret.
Mark inbound tasks with their source and suppress the echo, and check the source on the other side. Both guards, or the two systems will create tasks for each other forever.
Yes. Free accounts can create 25 tasks a day through the API. Reading is never limited, and webhooks are included.
With one API key, accepted as an Authorization bearer token, an X-API-Key header, a query parameter, or a field in the JSON body — whichever your tool makes easiest.
Contact id identifies the person and many tasks can share one. External id identifies that specific task and is the deduplication key. Using the contact id to deduplicate would make the second task for a client overwrite the first.
Send skip_webhooks on inbound writes so 0nTask does not echo the event back, and have the receiving system ignore events whose source is itself. Both guards are needed.
They can be. Register a shared secret and each delivery carries an HMAC signature header you can verify.
Yes. 0nTask is registered in 0nMCP, so MCP-capable assistants can list, create, update and delete tasks without you writing any integration code.
The API is included on the free plan, and reading is never limited.
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