Frequently asked questions
What is Impostor?
A fast, local, cross-platform API client (macOS & Windows) — a Postman-style workspace for HTTP, auth, scripting, WebSocket and gRPC, built on a Rust core in an OS-native webview instead of Electron.
Which platforms are supported?
macOS (universal — Apple Silicon and Intel) and Windows. Both are downloadable from the Download page.
Is it free?
The full client is free for individual use. Paid Pro and Team plans are launching soon for 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 stored in your OS keychain — never written to disk 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, and gRPC?
Yes. OAuth 2.0 (client-credentials and authorization-code + PKCE), mutual TLS with PEM or PKCS#12 client certificates, a WebSocket console, and a dynamic gRPC client (server reflection or .proto files).
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.