Impostor

Support

Need a hand with Impostor? Report a bug, grab the sample workspaces and mock server, or browse the FAQ below.

Report an issue Hit a bug or have a feature request? Open an issue on the public support repo and we'll take a look. Samples, examples & mock server All the sample workspaces, example requests, Postman test data, and the one-command Docker mock server live in the support repo — clone it and start sending.

Frequently asked questions

What is Impostor?

A lightweight, fast, local, cross-platform API client (macOS & Windows) that idles in tens of megabytes — a Postman-style workspace for HTTP, auth, scripting, WebSocket, gRPC and MCP, built on a Rust core in an OS-native webview instead of Electron.

How does Impostor compare to Postman?

It covers the same day-to-day ground — requests, environments, collections, auth, scripting, and a runner — as a native app rather than an Electron one, so it idles in tens of megabytes instead of hundreds. It's local-first: no account, no cloud sync, no forced sign-in, and your workspace is git-friendly YAML on your own disk. Your Postman v2.1 collections and environments import directly, and pm.* scripts run as they are.

Do I need an account or an internet connection?

Neither. Impostor runs entirely on your machine — download it and start sending requests. There's no sign-in, no telemetry, and nothing phones home; the only network traffic is the requests you make and the update check.

Which platforms are supported?

macOS (universal — Apple Silicon and Intel) and Windows. Both are downloadable from the Download page.

Is it free?

Yes — the Community Edition is the full client, free for non-commercial use. Commercial use needs a paid Pro or Team licence, which also adds support and team licensing — see Pricing.

Where is my data stored?

Everything stays on your machine. Workspaces are plain, git-friendly YAML files (one request per file), and credentials are encrypted at rest with a key held in your OS keychain — never stored in plaintext and never sent anywhere.

Can I import my Postman collections?

Yes — Impostor imports Postman v2.1 collections and environments, including auth, bodies, and scripts. You can also import from a cURL command.

Does it support OAuth 2.0, mTLS, gRPC, and MCP?

Yes. OAuth 2.0 (client-credentials and authorization-code + PKCE), mutual TLS with PEM or PKCS#12 client certificates, a WebSocket console, a dynamic gRPC client (server reflection or .proto files), and an MCP client (stdio or Streamable HTTP) for connecting to Model Context Protocol tool servers.

Is there an example workspace to try?

Yes — the support repo (github.com/TheImpostorApp/support) has a ready-to-open workspace covering every feature (HTTP, auth, TLS/mTLS, WebSocket, SSE, gRPC, MCP, and scripting), plus a one-command Docker mock backend the requests target. Clone it, open mock-workspace in Impostor, and start sending.

Is the macOS build notarized?

Yes — macOS builds are signed with an Apple Developer ID and notarized, so they open without Gatekeeper warnings. Windows code-signing is rolling out.

Still stuck? Open an issue on GitHub.