A fast, lightweight, git-native API client for developers who live in terminals and version control.

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What is Senda?

Senda is a desktop API client — a spiritual cousin of Bruno and Postman — where every collection is a plain folder of YAML files. No cloud account, no proprietary sync, no binary blobs. Open a collection, send requests, and commit the diff.

Built with Wails (Go) for the native shell and SolidJS for the UI, it ships to a ~24 MB binary using ~100 MB of RAM — compared to ~150 MB binary / ~400 MB RAM for Electron-based alternatives.

🤖 Heads up: Senda is largely AI-assisted ("vibe-coded") — most of the code and docs were written by pairing with Claude, with a human steering the direction. It's young and experimental — more on what that means in How this was built.

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Screenshots

Click to expand the screenshot gallery

Main interface — 3-pane shell

Collection open with request tree

Request editor

Sending a request and viewing the response

JSON body editor with syntax highlighting

Headers tab

Assertions / test runner

Pre/post-request scripting

Command palette

Appearance — 13 built-in themes

Mock server

Environments

Auth

Code generation

Import — curl, Postman, OpenAPI, HAR

Request history

Regenerate screenshots: cd frontend && bun run shots (or task shots:desktop from the repo root) drives the UI headlessly and rewrites every image, including the GIF. See docs/screenshots/README.md for the full process.

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Why Senda?

Problem with existing tools	How Senda solves it
Postman/Insomnia store collections in the cloud or proprietary formats	Plain YAML files — git diff works on your requests
Electron apps ship 150 MB binaries and use 400 MB RAM	Wails + native webview: ~24 MB binary, ~100 MB RAM
Bruno is close but bru files aren't universally readable	Standard YAML, no custom DSL
Sync conflict nightmares on team collections	Collections are folders — merge conflicts resolve naturally
Heavy UI frameworks cause jank on large responses	SolidJS fine-grained reactivity + virtualized CodeMirror 6

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Features

Core workflow

• HTTP methods: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS
• Collections: one folder per collection, one YAML file per request — fully git-trackable
• Multi-request tabs: open many requests at once; state persists across restarts
• Resizable panes: sidebar | request editor | response viewer; sizes saved between sessions

Request editor

• URL, method, query params, headers, body with per-row enable/disable toggles and count badges
• Body types: JSON, raw, form-urlencoded, multipart/form-data, GraphQL (with one-click schema introspection and field autocomplete)
• Format button: validates and pretty-prints JSON body in one click
• Auth: Bearer token, Basic, API key, OAuth 2 — per-request or inherited from collection

Response viewer

• Status badge, duration, size at a glance
• Headers and body tabs; body rendered in CodeMirror 6
• Large-response handling: Go caps inline body at 2 MiB; UI shows size and a "Show anyway" escape hatch
• Viewport rendering: only visible lines painted — 20 MB JSON stays smooth

Environments & variables

• Named environments (dev, prod, staging…) stored as YAML alongside requests
• {{var}} interpolation in URL, headers, and body
• Precedence: runtime (script) → environment → collection base → request
• Secrets: *.secret.yaml files are gitignored and merged at send-time only — never committed; edit them in-app (collection or per-environment) via the Manage secrets dialog, values masked with per-row reveal. Optional at-rest encryption (AES-256-GCM, key in the OS keychain) guards them against disk/backup theft; export the key as SENDA_SECRET_KEY to decrypt headless on a server/CI

Testing & assertions

• Define assertions per request: target / operator / value
• Targets: status code, response time, body size, JSON path, header values, raw body
• Operators: eq, neq, contains, notcontains, matches (regex), gt/gte/lt/lte, exists, notexists
• JSON Schema validation: set responseSchema: on a request and the response body is validated against it on every send — failures appear as assertion rows
• Assertions run on every send and in folder/load test runs

Scripting

• Pre-request script: modify headers, params, or body before send using a JS sandbox
• Post-request script: extract tokens, set variables, or log after the response arrives
• senda.setVar() / senda.getVar() — session-scoped runtime variables (highest precedence)
• Powered by Goja (Go-native JS engine); 5-second runaway guard

Running collections

• Folder runner: sequential execution of all requests in a folder — with timing, status, and assertion results per request
• Request chaining: reference an earlier response inline with {{res.<slug>.json.token}} (status / body / json.<path> / header.<name>) — no script needed
• Flows: declarative *.flow.yaml graphs (request / branch / setvar / loop / parallel / delay) for orchestration beyond the sequential runner; create/edit/delete them in-app (raw YAML with live validation) or by hand, run from the app or headless with senda run -flow. Graphs are validated before they run, so a dangling edge or bad start fails fast before any request fires — see docs/flows.md
• Load testing: concurrent virtual-user (VU) mode with configurable duration, target RPS, and max VUs; reports p50/p95/p99 latency and status distribution streamed live

Mock server

• Spin up a local HTTP server straight from YAML definitions in .senda/mocks/ — no code
• Rule routes (match method + path, pick a response variant) and stateful resource routes (in-memory CRUD that survives across requests until reset)
• {{...}} response templating (path params, fake data, uuid, now), named scenarios you can switch live, proxy passthrough, CORS, and hot-reload on file edits
• Generate mocks from an OpenAPI spec, scaffold bundled presets, or save a real response as a mock to turn a round-trip into a fixture
• Also runnable headless: senda mock

Security scanning

• Run an embedded pack of nuclei-compatible HTTP checks against the resolved URLs of every request under a folder
• Filter by severity and tags; preview the exact check count before you run; progress streams check-by-check
• Pull extra/updated templates from any nuclei-compatible Git repo into .senda/security/
• Scans send real probe traffic — only point them at APIs you own or are authorized to test

Realtime: WebSocket & SSE

• WebSocket: connect to ws:// / wss:// endpoints, send frames, and watch the live message log — variables and auth resolve the same as HTTP requests
• Server-Sent Events: connect to an SSE endpoint and stream events into the response view in real time

Import & code generation

• Import from: curl commands, Postman v2.0+ collections, OpenAPI 3.0 / 3.1 specs, HAR captures (Chrome DevTools "Copy all as HAR" — bulk requests + example responses, with optional record-and-replay mocks; secrets and static/analytics noise stripped on import)
• OpenAPI spec editor: imported specs are kept in .senda/openapi/ and editable in-app via a structured form (operation summary/description + request-body fields), written back in place so the rest of the document is preserved; each request links to its operation, pulling that operation's request-body JSON Schema into the body editor for validation + key autocomplete
• Export a response as HAR: turn any captured request/response into a shareable .har from the response panel
• Generate code: curl, fetch, httpie, Python requests, Go net/http
• Generate API docs: render a collection (or one folder) to Markdown or self-contained HTML via senda docs

Developer experience

• Command palette (Ctrl+K / Ctrl+P): fuzzy-search requests, switch environments, trigger actions
• Theming: 13 built-in themes (Catppuccin, Nord, VS Code, monochrome, pastel) with independent light/dark picks and a follow-the-OS system mode — see docs/theming.md
• Keyboard shortcuts: Ctrl+T new tab, Ctrl+N new request, Ctrl+W close tab, Ctrl+S save, Ctrl+Enter send, Ctrl+Tab / Page Up / Page Down cycle tabs
• History: every sent request logged to .senda/history.jsonl; browsable in the history panel
• File watch: auto-refreshes when a YAML file is edited externally (git pull, $EDITOR)
• Source control: a read-only panel showing working-tree-vs-HEAD changes for the collection — status-badged file list with a semantic per-field diff (URL / method / header changed) for request YAML, raw text diff for everything else; shells the system git
• Drag-and-drop: reorder requests and folders in the tree
• Cookie jar: persistent session cookies across sends and runs
• Proxy & mTLS: per-collection upstream proxy and client certificate (cert/key/CA, optional verify-skip); proxy URL and cert paths support {{var}} so machine-specific values stay out of git
• One binary, three modes: senda is pure Go (no webview) — bare senda opens the terminal UI, senda run is the headless CI runner, senda gui launches the desktop app. All share the same send pipeline.
• Terminal UI: senda (or senda tui) — interactive 3-pane TUI (tree | request | response) for working entirely in the terminal
• CLI runner: senda run — same send pipeline as the desktop app, scriptable in CI

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Data format

Collections are plain directories. A minimal layout:

my-api/
├── .senda/                          # all non-request files live here, keeping the root clean
│   ├── senda.meta.yaml         # collection metadata (name, base auth, base vars)
│   ├── senda.secret.yaml       # gitignored collection secrets overlay
│   ├── environments/
│   │   ├── dev.yaml            # environment variables
│   │   ├── prod.yaml
│   │   └── prod.secret.yaml    # gitignored secrets overlay
│   ├── mocks/                  # mock server definitions
│   ├── security/               # extra/synced scan templates
│   └── history.jsonl           # sent request log (auto-generated)
└── users/
    ├── senda.meta.yaml         # per-folder vars/auth stay inline next to requests
    ├── list-users.yaml
    └── create-user.yaml

Collections created by older versions (with senda.meta.yaml, environments/, mocks/ and .security/ at the root) are migrated into .senda/ automatically the first time they are opened.

A single request file looks like this:

name: Create user
method: POST
url: "{{baseUrl}}/users"
headers:
  - { key: Content-Type, value: application/json, enabled: true }
  - { key: Authorization, value: "Bearer {{token}}", enabled: true }
body:
  type: json
  raw: |
    { "name": "Ada Lovelace", "email": "ada@example.com" }
asserts:
  - { target: status, op: eq, value: "201" }
  - { target: body, op: contains, value: "ada@example.com" }
preScript: |
  req.setHeader("X-Request-ID", senda.getVar("requestId") || crypto.randomUUID());
postScript: |
  senda.setVar("userId", res.json.id);

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Install

Prebuilt binaries for Linux, macOS, and Windows are attached to every release. Each archive bundles the everyday senda binary (pure Go — terminal UI plus senda run/mock/docs and the senda gui launcher) and the senda-desktop GUI app. Pick whichever install path you prefer.

Shell installer (Linux / macOS)

curl -fsSL https://raw.githubusercontent.com/this-senda/senda/main/scripts/install.sh | sh

Installs into ~/.local/bin (or /usr/local/bin when writable). Override with SENDA_INSTALL_DIR=/path, pin a version with SENDA_VERSION=0.1.0, or skip the GUI on headless hosts with SENDA_NO_DESKTOP=1. The script verifies the release SHA-256 checksum before installing.

Linux: the senda-desktop window needs a WebKitGTK runtime — libwebkitgtk-6.0-4 (Debian/Ubuntu), webkitgtk-6.0 (Arch), or webkitgtk6.0 (Fedora). The installer prints the exact command if it's missing.

PowerShell installer (Windows)

irm https://raw.githubusercontent.com/this-senda/senda/main/scripts/install.ps1 | iex

Homebrew (macOS / Linux)

brew install this-senda/tap/senda

winget (Windows)

winget install this-senda.Senda

Prefer Chocolatey? choco install senda works too.

Maintainer notes for cutting releases and publishing the Homebrew/Chocolatey manifests live in packaging/README.md.

Unsigned builds

Senda's binaries aren't code-signed yet, so the OS shows a one-time warning on first launch. The download is intact (verify the checksum if you like) — this is just the missing signature, not a problem with the app.

• macOS — the .dmg is the recommended GUI download (drag Senda.app to Applications). On first launch Gatekeeper blocks the unsigned app — on Apple Silicon it usually shows "Senda is damaged and can't be opened" (older Macs may instead say "developer cannot be verified"). The "damaged" dialog can't be cleared by right-clicking → Open — you must remove the quarantine flag once:

  xattr -dr com.apple.quarantine /Applications/Senda.app

  (The "developer cannot be verified" variant also clears with right-click → Open.) The download is fine — this is only the missing Apple signature. The shell installer instead drops the CLI-style senda / senda-desktop binaries and clears their quarantine flag for you. Homebrew also installs those binaries but re-applies quarantine by default — install with brew install --no-quarantine this-senda/tap/senda to skip it.

  Downloading a .tar.gz straight from the releases page (instead of via the installer) quarantines both binaries, and the same block hits the terminal senda CLI/TUI — not just the GUI. Clear them after extracting:

  xattr -dr com.apple.quarantine ./senda ./senda-desktop

• Windows — SmartScreen may show "Windows protected your PC". Click More info → Run anyway.

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Getting started

Building from source — for contributors and anyone on an unsupported platform.

Prerequisites

Tool	Version	Purpose
Go	1.25+	Build the backend (go.mod targets 1.25.7)
Bun	1.x	Frontend install, build, test
Wails CLI v3	alpha2.104+	Dev server + build
webkitgtk	6.0 (4.1 legacy)	Native webview (Linux only)

Install Wails:

go install github.com/wailsapp/wails/v3/cmd/wails3@latest

On Linux, install the webview dependency (the default build targets GTK4 / webkitgtk-6.0):

sudo pacman -S webkitgtk-6.0          # Arch  (legacy: webkit2gtk-4.1)
sudo apt install libwebkitgtk-6.0-dev # Ubuntu/Debian (legacy: libwebkit2gtk-4.1-dev)

On macOS and Windows, WebKit / WebView2 is bundled — no extra step needed.

Run in development (hot reload)

# Clone and enter
git clone https://github.com/this-senda/senda.git
cd senda

# Install frontend dependencies
cd frontend && bun install && cd ..

# Start the app with hot reload (Vite HMR + Go auto-restart)
wails3 dev

wails3 dev always runs the default GTK4 / webkitgtk-6.0 stack on Linux. To fall back to the legacy GTK3 / webkit2gtk-4.1 webview, build with the gtk3 tag (see below).

Build a release binary

# Single command (rebuilds frontend, embeds assets, compiles Go) → bin/senda-desktop
wails3 build

# Or run the OS-namespaced task directly (swap linux for darwin / windows):
wails3 task linux:build          # stripped release (~24 MB) → bin/senda-desktop
wails3 task linux:build:debug    # unstripped, keeps symbols/DWARF (~32 MB)

./bin/senda-desktop

Build tags: the Taskfile applies the mandatory production tag for you. If you call go build directly you must pass -tags production (go build -tags production -o bin/senda-desktop .) or the binary exits with an error at startup. The default (no extra tag) selects GTK4 / webkitgtk-6.0 on Linux; to use the legacy GTK3 webview, add gtk3: wails3 task linux:build PROD_TAGS="production gtk3".

Run tests

# Go backend tests
go test ./...

# Frontend unit tests (Vitest) — runs without the Wails toolchain; the
# generated bindings are stubbed under test (see frontend/vite.config.ts)
cd frontend && bun run test

# Visual screenshot regeneration (Playwright drives a mocked backend)
task shots:desktop  # or, from frontend/: bun run shots

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Tech stack

Layer	Technology	Reason
Desktop shell	Wails v3 (Go)	Small binary, native webview, Go for HTTP/file ops
Frontend	SolidJS + TypeScript	Fine-grained reactivity, tiny bundle, minimal re-renders
Editor	CodeMirror 6	Virtualized viewport — handles 20+ MB without freeze
Storage	Plain YAML (gopkg.in/yaml.v3)	Git-diffable, human-readable, no custom DSL
Frontend tooling	Bun (never npm/node)	Fast install, unified build/test/run
Scripting engine	Goja	Pure-Go JS VM — no Node dependency, sandboxed
Visual testing	Playwright	Screenshot-based UI verification

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Project structure

senda/
├── frontend/src/
│   ├── App.tsx                   # 3-pane shell, keyboard shortcuts, file-watch events
│   ├── components/               # UI components (Sidebar, RequestEditor, ResponseViewer, …)
│   └── lib/                      # store, api bindings, actions, format helpers
│
├── internal/
│   ├── model/                    # Core structs (Request, Response, KV, Body, …)
│   ├── httpclient/               # HTTP send, streaming, timeout, size tracking
│   ├── pipeline/                 # Unified send pipeline (pre-script → vars → send → asserts → schema → post-script)
│   ├── store/                    # YAML serialization, filesystem tree walk, file watch
│   ├── vars/                     # {{var}} interpolation resolver + precedence
│   ├── script/                   # Goja JS sandbox (pre/post scripts)
│   ├── assert/                   # Assertion evaluator
│   ├── schemaval/                # JSON Schema response validation
│   ├── auth/                     # Auth scheme helpers (Bearer, Basic, API key, OAuth 2)
│   ├── runner/                   # Sequential folder runner (+ data-driven runs)
│   ├── load/                     # Concurrent load test engine
│   ├── codegen/                  # Code generation (curl, fetch, httpie, python, go)
│   ├── importer/                 # Import from curl / Postman / OpenAPI / HAR
│   ├── docgen/                   # Markdown / HTML API docs from a collection
│   ├── mockserver/               # Local mock server (rules, resources, scenarios)
│   ├── security/                 # Nuclei-compatible security scanner
│   ├── wsclient/ · sseclient/    # WebSocket + Server-Sent Events clients
│   ├── history/                  # JSONL-based request history
│   ├── scm/                      # Read-only git diff (working tree vs HEAD), semantic per-field for request YAML
│   ├── aigen/                    # Optional LLM-assisted assertion suggestions
│   ├── tui/                      # Terminal UI (Bubble Tea; same pipeline, no webview)
│   ├── termimg/                  # Pure-Go TUI screenshot/GIF renderer (docs)
│   └── buildinfo/                # Version string injected at build time
│
├── cmd/senda/                     # Unified pure-Go binary: TUI default + run/mock/docs + gui launcher (no webview)
├── app.go                        # Wails-bound API surface (IPC)
├── app_features.go               # Import, codegen, runner, load, mock, history, WS/SSE
├── app_security.go               # Security-scan bindings
├── app_watch.go                  # File watcher integration
├── docs/                         # architecture, roadmap, design decisions (ADRs)
└── examples-collection/          # Sample collection (JSONPlaceholder, GitHub API, …)

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Example collection

The examples-collection/public-api/ directory contains a ready-to-open collection with:

• Postman Echo — verify request/response capture (headers, auth, form data)
• JSONPlaceholder — realistic CRUD workflow (list, create, update, delete)
• GitHub API — real-world authenticated requests

Open it via File → Open Collection and set the token environment variable to your GitHub PAT to run the GitHub folder.

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Headless runner (senda run)

senda run drives the same send pipeline as the desktop app — scripts, variables, secrets, assertions, and the cookie jar all behave identically — so it slots straight into CI. It exits 0 when every request passes and 1 on any failure.

task build:senda                              # builds bin/senda

# Run a collection (or one folder) against an environment
bin/senda run -collection ./my-api -env dev
bin/senda run -collection ./my-api -folder auth -env dev -q   # -q = summary only

# Data-driven run: repeat every request once per row of a CSV/JSON file
bin/senda run -collection ./my-api -data users.csv

# Run a flow (branch/loop/chained requests) by name or path
bin/senda run -collection ./my-api -flow signup

# Machine-readable run report for CI (json or junit XML; -o file or stdout)
bin/senda run -collection ./my-api --report junit -o report.xml
bin/senda run -collection ./my-api --report json

# Generate API documentation (Markdown or self-contained HTML)
bin/senda docs -collection ./my-api -o docs/api.md
bin/senda docs -collection ./my-api --docs-format html -o docs/api.html

# Run the mock server headlessly (see docs/mock-server.md)
bin/senda mock -collection ./my-api -addr :8787 -scenario error
bin/senda mock init oauth -collection ./my-api   # scaffold a preset

Regenerate the CLI screenshot + GIF: task shots:cli runs the real pipeline against a local in-process server and renders the actual output (a still PNG and the animated GIF) into docs/screenshots/cli/ in pure Go — no network, no capture tools. SENDA_CLI_GIF=0 skips the GIF.

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Terminal UI (senda)

A keyboard-driven TUI built on Bubble Tea that drives the exact same send pipeline as the desktop app — no webview, pure Go. It's what bare senda opens (when attached to a terminal). Useful over SSH, in tmux, or when you'd rather not leave the terminal.

task build:senda                          # builds bin/senda
bin/senda                                 # open the current directory
bin/senda -collection ./my-api            # open a collection (shorthand for `senda tui`)
bin/senda tui -collection ./my-api -env dev

# or build + run in one step
task tui -- -collection ./my-api -env dev

Three panes: collection tree | request detail | response body.

Key	Action
j / k or ↑ / ↓	Move in the tree
enter / l / →	Expand folder · load request
h / ←	Collapse folder
s	Send the selected request
e	Edit the request file in $EDITOR
[ / ]	Cycle environments
tab	Switch focus (tree ↔ response, for scrolling)
q / Ctrl+C	Quit

Click to expand the terminal screenshot gallery

Three-pane shell — tree · request · response

Tests + timing waterfall

Command palette (Ctrl+K)

Environments manager

Code export

WebSocket — live connection log

Layouts — stacked and focus

Regenerate terminal screenshots: task shots:tui (from the repo root) renders every TUI image and the GIF headlessly in pure Go — no PTY or ffmpeg. See docs/screenshots/tui/README.md for the full process.

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Keyboard shortcuts

Shortcut	Action
Ctrl+T	New tab
Ctrl+N	New request
Ctrl+W	Close active tab
Ctrl+S	Save request
Ctrl+Enter	Send request
Ctrl+Tab	Next tab
Page Up / Page Down	Cycle tabs
Ctrl+K / Ctrl+P	Open command palette

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Roadmap

Senda v0.1 is feature-complete for everyday API work — see Features for what's in the box, and the CHANGELOG for the full release detail.

Where it's headed next — intent, not a promise. The full roadmap lives in docs/roadmap.md.

• gRPC — first-class gRPC requests alongside HTTP and GraphQL

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How this was built

Senda is largely vibe-coded — most of the code, tests, and docs were written with heavy AI assistance (Claude), with me steering the direction and deciding what shipped. It's young, lightly used, and maintained by one person, so treat it as experimental. The source is plain Go and YAML, so when in doubt, read the diff. Catch something off? Open an issue.

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Contributing

Contributions are welcome. Please open an issue before starting larger changes.

See CONTRIBUTING.md for setup, test commands, conventions, and PR guidelines.

Architecture references:

• docs/architecture.md — system design, IPC contract, data model
• docs/decisions/ — Architecture Decision Records (ADRs)

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License

MIT — see LICENSE.