Open-source alternatives to Postman: 3 API client tools compared
The question is not which client has more buttons, it is where your collections and the tokens inside them are stored, and that decides how much of your API work can be reviewed in Git. usebruno/bruno is the one most readers should look at first, because a collection is a folder of plain text files in your own repository.
What Postman does, and why people look elsewhere
Postman is an API client for sending HTTP requests, organising them in collections, writing tests and sharing them in a hosted workspace.
- collections sync to Postman's cloud by default, including request bodies and tokens
- collaboration features are tied to a per-user plan
- the proprietary collection format
The candidates at a glance
| Project | Licence | Maintenance | Language | GitHub stars | Install |
|---|---|---|---|---|---|
| usebruno/bruno | MITPermissive: commercial use allowed | Commits in the last six monthsLast push November 6, 2026 | JavaScript | 48,267 | Command documented |
| hoppscotch/hoppscotch | MITPermissive: commercial use allowed | Commits in the last six monthsLast push November 5, 2026 | TypeScript | 80,763 | See analysis |
| Kong/insomnia | Apache-2.0Permissive: commercial use allowed | Commits in the last six monthsLast push November 7, 2026 | TypeScript | 40,133 | See analysis |
Each alternative in detail
usebruno/brunoOpensource IDE For Exploring and Testing API's (lightweight alternative to Postman/Insomnia)
- Best for
- Your team already reviews code in Git and you want API requests to travel through the same pull request path with no cloud account involved. A collection is a directory of .bru files in a plain text markup language, and the CLI runs them with bru run, including a single request or a folder against a named environment.
- What you give up
- The README states Bruno is offline-only and that there are no plans to add cloud sync, so there is no hosted workspace, no shared collection browser and no browser-based client. That is a deliberate trade rather than a missing feature. The MIT licence also covers the open source code only, and the paid versions and the Bruno trademark sit outside it.
- First install step
- Full setup guide
# On Mac via Homebrew brew install bruno # On Windows via Chocolatey choco install bruno # On Windows via Scoop scoop bucket add extras scoop install bruno
hoppscotch/hoppscotchOpen-Source API Development Ecosystem • https://hoppscotch.io • Offline, On-Prem & Cloud • Web, Desktop & CLI • Open-Source Alternative to Postman, Insomnia
- Best for
- You want one client for HTTP, GraphQL, WebSocket, Server-Sent Events, Socket.IO and MQTT, and you would rather have a browser tab than another desktop application. It installs as a Progressive Web App, supports cURL import, and exports collections as a file or a GitHub gist.
- What you give up
- Our analysis of Hoppscotch is blunt that this is not a drop-in Postman replacement for collection runners and CI pipelines, so a team that leans on those has to change habits. Self-hosting also brings real configuration: DATA_ENCRYPTION_KEY has to be a real 32-character value rather than the placeholder in .env.example, WHITELISTED_ORIGINS has to list the exact origins you serve from, and the docker-compose profile you pick has to match your database situation.
Kong/insomniaThe open-source, cross-platform API client for GraphQL, REST, WebSockets, SSE and gRPC. With Cloud, Local and Git storage.
- Best for
- You want one client that speaks REST, GraphQL, gRPC, WebSockets and Server-Sent Events, and you want storage to be a per-project decision: Local Vault for work that never leaves the machine, Git Sync for collections that should go through review, Cloud Sync for shared editing.
- What you give up
- An account is required for most capabilities, and the README states plainly that Insomnia does not require one only if you use the local Scratch Pad. The README also lists unlimited collaboration, Git Sync, project organizations and third-party IDP login as premium capabilities, so the collaboration model is where the open source stops. It is an Electron application as well, which is a heavier install than a browser tab or a CLI.
Where the collection lives: a folder, a server, or a choice per project
Postman is an API client for sending HTTP requests, organising them in collections, writing tests and sharing them in a hosted workspace. People look elsewhere for three reasons. Collections sync to Postman's cloud by default, request bodies and tokens included. Collaboration features are tied to a per-user plan. And the collection format is proprietary, so leaving means leaving with nothing portable.
Those three reasons produce three different answers, and they are not really about features.
usebruno/bruno removes the cloud from the model entirely. The README says Bruno stores your collections directly in a folder on your filesystem, using a plain text markup language called Bru, and that you can use Git or any other version control to collaborate over them. It then says Bruno is offline-only and that there are no plans to add cloud sync, ever, and gives the reason: the data should stay on your device. That is a stronger statement than a feature list, and it is the reason the project is a good fit for a team that already reviews everything else in pull requests.
hoppscotch/hoppscotch goes the other way and makes the client a service. It is an ecosystem with web, desktop and CLI paths, and a self-hosted deployment you start with a compose profile. The README lists HTTP with custom methods, GraphQL with schema introspection, WebSocket, Server-Sent Events, Socket.IO and MQTT, plus authorization modes covering none, basic, bearer token, OAuth 2.0 and OIDC with PKCE, pre-request scripts written in JavaScript, nested collections, workspaces, teams, and a proxy mode for working around CORS.
Kong/insomnia takes a third position, which is the most interesting of the three: storage is a decision you make per project rather than a setting for the whole product. The README describes Local Vault for full local storage, Git Sync that writes to any third party Git repository without going through the cloud, and Cloud Sync for collaboration with optional end-to-end encryption in the cloud. It also has Private Environments, where environment configuration is always stored locally no matter which backend the project uses.
Left out, and worth saying why: HTTP mocking servers and load testing tools, which are separate products that happen to sit next to API clients, and the older desktop clients with large installed user bases, which are the same trade in a different wrapper.
Choosing by scenario: a solo developer, a small team, a company that cannot send data out, a team automating HTTP in CI
Where your work sits decides which of the three fits, more than any protocol list.
A solo developer who wants a client that leaves no trace anywhere should look at usebruno/bruno. The install is a package manager command, collections are files, and there is no account to create. Our analysis of Bruno makes one specific warning: whatever CLI version you install has to match the desktop app your colleagues are running, and any secrets in environment files have to stay out of the repository.
A small team that already lives in Git gets the same benefit and the same obligation. The review of a .bru file diff looks like the review of any other source change, which means a request body change is a pull request rather than a settings change. The cost is that environments are files too, so the question of where a token lives has to be answered deliberately.
A company that cannot send request data to a vendor has two paths. hoppscotch/hoppscotch, self-hosted, keeps the client on infrastructure the team runs, and the analysis says the thing to verify first is not the software but the configuration: the encryption key, the whitelisted origins and the compose profile. Kong/insomnia answers it differently, by letting a sensitive project live entirely in the Local Vault while other projects collaborate in the cloud, with a note in the README that having an account is not tied to how you store sensitive data.
A team that needs to run requests in a pipeline is best served by usebruno/bruno, and this is where its CLI is the strongest feature. The README documents npm install -g @usebruno/cli, running every request in a collection, running a single request file, and running a folder against a named environment, and it publishes official Docker images on Docker Hub and the GitHub Container Registry with alpine and debian variants for linux/amd64 and linux/arm64. Insomnia also has a native CLI for linting and testing, and a mocking server that can be self-hosted, so the choice is between a text format you can review and a fuller testing suite.
What each one costs to run, and what it costs to keep in CI
Two of these three are desktop applications, which is worth saying plainly because that is the largest install difference most teams will notice.
usebruno/bruno ships as a binary for Mac, Windows and Linux and is also available through Homebrew, Chocolatey, Scoop, Snap, Flatpak, Apt and the AUR. Nothing runs on a server, so there is no database to patch and nothing to back up beyond your own repository. The command on this page is a single package manager install, and the same project also publishes CLI images, so the CI runner never needs Node.js installed on the host.
hoppscotch/hoppscotch is the only one of the three with a server component, and the command on this page is docker compose --profile default up, which tells you the profile is a choice rather than a detail. A self-hosted instance is a web application with a database behind it, so it needs upgrades, a backup and an eye on who can reach it. The trade is that every developer in the team gets the same client URL instead of installing anything.
Kong/insomnia is an Electron application, so the install is larger than either of the others, and the command on this page is a source build: npm i, then npm run inso-start, then running the inso binary from packages/insomnia-inso/bin. That is a monorepo with many Node packages, and our analysis of Insomnia notes the engines declared in package.json require Node 24.18.0 or later and npm 11 or later if you intend to build from source rather than download the app.
What all three share is the CI question, and it is the one people underestimate. An API client on a developer's laptop is a convenience. An API client in a pipeline is a dependency you have to version, pin and keep compatible with the collection format, and the collection format is what the team actually owns.
Licences: permissive throughout, with one trademark exception
This is the easiest licence picture on the site, and the interesting detail is not the licence but where the product stops being open.
usebruno/bruno and hoppscotch/hoppscotch are MIT. Kong/insomnia is Apache-2.0. All three let a company read the source, modify it, and run a modified version internally without publishing anything, and all three are comfortable answers in a legal review.
The exception is worth reading carefully. Our analysis of Bruno notes that the MIT licence covers the open source code, while the paid versions and the Bruno trademark sit outside it. That is an ordinary commercial arrangement rather than a restriction on the code, but it does mean a company that rebrands a Bruno-based internal tool is in a different conversation from one that forks it and keeps the name.
Insomnia raises a related point in a different form. Its Apache-2.0 licence covers the client, while the collaboration surface is a commercial product, and the README is explicit that the ability to keep building the open source distribution depends on converting a subset of free users into paying customers. That is a business-model statement rather than a licence term, and it is the reason the README also spells out that Local Vault keeps sensitive projects entirely local even for users who have an account.
One practical note across all three. Whatever you pick, the collection format is the thing your team owns, and a format you can diff in Git is worth more over five years than any feature in the client that reads it.
Bottom line
Pick usebruno/bruno when your team reviews everything in Git and you want no cloud account in the loop, hoppscotch/hoppscotch when you need HTTP, GraphQL, WebSocket, SSE, Socket.IO and MQTT in one browser-based client you host yourself, and Kong/insomnia when storage needs to be decided per project and you want the widest protocol coverage including gRPC. Before committing, check that your .bru or exported collection diffs cleanly in review, set a real encryption key and origin list on any self-hosted Hoppscotch, and read which Insomnia capabilities are premium rather than open source.
Sources
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