# How Fous works

> How Fous turns a website into a typed API method, and how that compares with browser agents and scripts you maintain yourself.

Source: https://docs.fous.com/guides/how-it-works
Index: https://docs.fous.com/llms.txt

Fous turns any website, including one behind a login, into an API that your software and AI agents can call. You name a site and say what you want to read or do there. Fous builds a **method**: one thing that website can do, as a typed API call.

## What a build makes

A [build](https://docs.fous.com/guides/builds.md) starts from a request in plain words. Fous studies how the site works, writes the method and tests it on real inputs, usually in about a minute. The result is saved to your organization with an `input_schema` and an `output_schema`, so calling it looks like any other API.

A method either reads data (`effect: "read"`) or does something on the site (`effect: "write"`), such as filling in a form. [Workflows](https://docs.fous.com/guides/workflows.md) chain methods together on a schedule or from a webhook.

## What happens on a run

[Running a method](https://docs.fous.com/guides/runs.md) executes the method saved at build time with your input. No AI model decides what to click or where to look: the same method runs every time, and the output fits the same schema. A failed run costs nothing.

Pages behind a login run with a saved login or API key, kept as a [connection](https://docs.fous.com/guides/connections.md).

## When a site changes

Sites change, and a method built on one can stop working. Fous [checks every method version in use](https://docs.fous.com/guides/status.md) and repairs it in place. The repair keeps your `input` and the shape of `data`, so your code does not change, and it costs nothing. A change you ask for that alters the inputs or outputs makes a new version, and your calls keep running the current one until you [switch to it](https://docs.fous.com/guides/methods.md#versions).

## Compared with other approaches

| | Fous method | AI browser agent | Script you maintain |
| --- | --- | --- | --- |
| On each call | Runs the saved method | A model reads the page and decides | Runs your code |
| Output | Fits a typed schema every time | Whatever the model returns | Whatever your code parses |
| When the site moves | Fous repairs it in place | The model may adapt, or fail differently | It breaks until you fix it |
| Logins and 2FA | Saved connection, signed in again by Fous | Handled in the session, if at all | You store and refresh sessions yourself |
| Writing to a site | A method marked `write`, sent only when you call it | The model decides what to send | Your code |

Start with the [Quickstart](https://docs.fous.com/quickstart.md), or connect an agent through the [MCP server](https://docs.fous.com/guides/mcp.md).