Napper vs Postman
Napper is a free, open-source, CLI-first alternative to Postman for API testing. Here is how they compare.
What is the main difference between Napper and Postman?
Postman is a GUI-first application with a standalone desktop client. The command line interface (Newman) is a secondary tool. Napper takes the opposite approach: the CLI is the primary product, and the VS Code extension provides a visual interface within your existing editor.
Does Napper require an account?
No. Napper requires no account, no sign-up, and no cloud sync. Postman requires an account to use the desktop application and locks collaboration features, advanced scripting, and API monitoring behind paid tiers.
How do file formats compare?
Postman stores collections as JSON blobs that are difficult to read in diffs and code reviews. Napper stores every request as a plain text .nap file, every test suite as a .naplist file, and every environment as a .napenv file. All formats are human-readable and produce clean git diffs.
How does scripting compare?
Postman provides a sandboxed JavaScript environment with a limited set of built-in libraries. Napper uses F# Interactive (.fsx scripts) with full access to the .NET ecosystem. You can parse XML, call databases, generate cryptographic tokens, validate JSON schemas, and reference any NuGet package.
How does CI/CD integration compare?
Postman requires Newman (a separate npm package) for running collections from the command line. Napper is CLI-first with a self-contained binary and no runtime dependencies. It outputs JUnit XML, TAP, JSON, and NDJSON formats natively.
Feature comparison
| Feature | Napper | Postman |
|---|---|---|
| CLI-first design | Yes | No (Newman is secondary) |
| VS Code integration | Native extension | Separate app |
| Git-friendly files | Plain text .nap files |
JSON blobs |
| Assertions | Declarative + F# scripts | JavaScript scripts |
| Scripting | Full F# with .NET access | Sandboxed JavaScript |
| CI/CD output | JUnit, TAP, JSON, NDJSON | Via Newman |
| Test Explorer | Native VS Code support | No |
| Account required | No | Yes |
| Pricing | Free, MIT license | Freemium with paid tiers |
When should you choose Napper over Postman?
Choose Napper if you want a tool that lives in your terminal and editor, stores everything as plain text in your repository, runs natively in CI/CD without additional dependencies, and gives you the full power of F# for advanced scripting. Choose Postman if you need a standalone GUI application with built-in collaboration features and cloud-based team workspaces.