# Introduction

> What the Noptcha API does, its two APIs, and where to start.

Source: https://noptcha.com/docs/

Noptcha is a captcha solving API. You send a **task** (the captcha type and the parameters of the page that shows it), Noptcha solves it, and you get a **solution** (a token, cookies, text or the selected images). You pay only for solved tasks.

## Two APIs, one account

Both APIs live on `https://api.noptcha.com` and share keys, prices, balance, task state and limits. A task created through one can be read through the other.

|  | [Compatibility API](https://noptcha.com/docs/compatibility-api.md) | [Native API (v1)](https://noptcha.com/docs/native-api.md) |
| --- | --- | --- |
| Protocol | anti-captcha compatible JSON: `POST /createTask`, `/getTaskResult`, `/getBalance` | REST + JSON under `/v1/` |
| Key | `clientKey` in the body | `Authorization: Bearer <key>` |
| Errors | always HTTP 200; `errorId` and `errorCode` | HTTP status + RFC 9457 problem details |
| Waiting | poll `getTaskResult` | `Prefer: wait=N` waits up to 90 seconds in the same request, or poll |
| Retries | — | `Idempotency-Key`: a retried request never creates a second task |
| Task IDs | integers | strings (the same number) |
| Use it when | you already have software for the anti-captcha protocol | you write a new integration |

There is also a [2captcha legacy API](https://noptcha.com/docs/2captcha-api.md) (`/in.php`, `/res.php`) for software written for that protocol.

## How a task works

1.  Create a task with a type and its parameters ([task types](https://noptcha.com/docs/task-types.md)).
2.  Wait for the result: poll, or ask the v1 API to wait for you.
3.  Use the solution on the target site. Report whether it worked, if you like: reports are recorded as a quality signal (they do not refund).

Results are kept for 10 minutes after a task completes.

## Next steps

-   [Quickstart](https://noptcha.com/docs/quickstart.md): solve a first task with a free test key.
-   [Keys and authentication](https://noptcha.com/docs/authentication.md) and the [sandbox](https://noptcha.com/docs/sandbox.md).
-   [Errors](https://noptcha.com/docs/errors.md), [rate limits](https://noptcha.com/docs/limits.md), [versioning](https://noptcha.com/docs/versioning.md).
-   [API reference](https://noptcha.com/docs/api-reference.md), generated from the [OpenAPI description](https://noptcha.com/openapi.json).
-   For AI agents and tools: [llms.txt](https://noptcha.com/llms.txt) and [llms-full.txt](https://noptcha.com/llms-full.txt) contain this documentation as plain text.