Documentation

FastDev is a high-performance mocking engine designed to eliminate backend dependencies. Deploy programmable endpoints with persistent state in under 30 seconds.

✨ AI Generator

New

Describe your API logic in plain English, and FastDev will instantly generate a fully functional Python handler with persistence and validation.

How it works

Prompt: Explain what the endpoint should do (e.g., "Create a user with email validation and return a JWT").
Formats: Specify Input (e.g., JSON) and Output (e.g., JSON) expectations.
Initial State: Optionally provide seed data (e.g., {"users": []}) for the mock to start with.
Deploy: Click "Generate & Deploy" to get your live endpoint instantly.

Custom Base Paths

Organize your mocks under custom namespaces (Base Paths) or group them under existing ones.

Existing IDs

Select from your previously created Base Paths to add new routes (e.g., `/api/v1` → add `/users`, `/posts`).

Create New

Define a unique ID (e.g., `my-project-api`). We verify availability instantly to ensure no collisions.

Authentication & Security

FastDev provides secure access to your mocks while allowing for public sharing.

●Extended Sessions: Login sessions now last for 30 days, so you don't receive interruptions during development.
●Visibility Control: Mark endpoints as Public (accessible by anyone) or Private (only visible to you).

Registry & Monitoring

The Registry is your central hub for managing all deployed endpoints.

Key Features

Detailed View: Click "View Details" to see the full configuration, code, and initial data of any endpoint.
Filtering: Automatically shows your private endpoints and all public endpoints.
Live Updates: Endpoints are active immediately upon creation.

def handler(url, headers, body, data):

Functional mocks inject your request into a restricted Python environment. This allows for dynamic logic, header-based auth, and persistent state.

The Parameters

Param	Type	Description
url	string	The full request URL.
headers	dict	Incoming HTTP headers.
body	any	Parsed JSON or raw body string.
data	dict	Persistent state (Read/Write).

Example: Stateful Counter

Important Constraints

To ensure system stability, functional mocks have a 2.0s execution timeout and cannot access the Python standard libraries (os, sys, etc.).

Persistent variables in data are saved automatically after execution.