Paste anything; Decant detects the format and converts it — plus a set of focused developer tools. Native macOS app (SwiftUI + AppKit, macOS 14+). Everything runs locally.
Decant is open source and free — forever. No accounts, no telemetry, no network calls, no paid tier, no "pro" features.
Download Decant-<version>.zip from Releases, unzip, and move Decant.app to Applications. Builds are signed and notarized. To update, download the newer release; watch the repo for "Releases only" to get notified.
Or build it yourself (needs Xcode 26 / Swift 6):
git clone https://github.com/techtheoryio/decant.git && cd decant
scripts/build-app.sh 0.0.0 && open .build/Decant.appFor development:
swift run Decant # build and launch
swift test # engine tests| Category | Tools |
|---|---|
| Format | Auto Detect (New), Formatter (JSON tree/query/repair; JS, TS, CSS, SCSS, Less, HTML, XML, Markdown, YAML, GraphQL), Markdown preview, OpenAPI editor with a Scalar API reference preview |
| Encoding | Base64 (text and files, URL-safe, padding, MIME wrap, data: URIs, magic-byte detection), URL encode with query table |
| Time | Unix time (live clock, results table, date picker, time zones, differences), Cron (plain words, next runs) |
| Tokens & Security | JWT decoder with HMAC check, UUID v4/v7 + ULID generator and inspector, password generator |
| Data | CSV ↔ JSON with table preview, JSON ↔ YAML (YAML 1.2, anchors and merges) |
| Text | Diff (side by side / unified, word highlights, folding), Git Diff cleanup for AI review (drops lockfiles, generated and binary files; path filters), Regex tester, character/word/line counter |
| Miscellaneous | Color converter (color panel, eyedropper, contrast), QR code generator and reader |
Shortcuts: ⌘K command palette, ⌘1–⌘9 tools (order from Settings → Sidebar), ⌘N new document, ⌘O open file, ⌘S save output, ⇧⌘C copy output, ⌘F find in output, ⌘+ / ⌘− font size, ⌥⌘Z wrap lines.
Decant's main feature is what it leaves out. Every tool has to earn its place, and the bar is high:
- Daily use. A tool belongs here if developers reach for it every week, not once a year.
- Offline and local. Nothing leaves your machine. No features that need a server, an API key, or a login.
- Zero dependencies. Only Apple's frameworks. Optional external tools (Biome, Prettier) are used when you already have them, never bundled. The one exception is the OpenAPI preview, which ships Scalar's prebuilt script so it works offline.
- Fast to open, fast to use. Paste, get the answer, move on. No setup, no onboarding, no settings you have to learn first.
- Deleting beats adding. A smaller, sharper app is better than a bigger one. We remove things that don't pull their weight.
If an idea doesn't fit, that's not a judgment on the idea — it probably makes a great standalone tool.
Bug fixes, polish, and better behavior of existing tools are always welcome — just open a PR.
For a new tool or a bigger change, open an issue first so we can talk about whether it fits the list above before you spend time on it.
Ground rules for PRs:
- Keep the diff focused. One change per PR.
- No new dependencies.
- Logic goes in
Sources/DecantCorewith a test inTests/DecantCoreTests;swift testmust pass. - Match the surrounding code style. Less code is better code.
Sources/DecantCore— deterministic engine and tool logic, no UI.Sources/Decant— the app.- History lives in
~/Library/Application Support/Decant/history.json; retention and size are set in Settings → History. Pinned entries are kept. - The Formatter uses Biome or Prettier when either is on your login-shell
PATH(looked up viazsh -lic), Biome first for the languages it supports. Without them it falls back to the built-in JSON and JS/TS formatters and Foundation's XML/HTML pretty-printer; other languages are shown unformatted. - OpenAPI preview:
Sources/Decant/Resources/scalar.jsis the standalone build of@scalar/api-reference(MIT), currently 1.73.1. To update, replace it withhttps://cdn.jsdelivr.net/npm/@scalar/api-reference@<version>/dist/browser/standalone.js. Telemetry, the AI agent, MCP and web fonts are turned off inScalarView; "Test Request" still sends requests to the API's servers when you click it. - App icon: source
Assets/AppIcon.svg; after editing runAssets/make-icon.sh(needsrsvg-convert) to rebuildSources/Decant/Resources/AppIcon.icns. - Releasing: push a
v1.2.0-style tag;.github/workflows/release.yamlruns the tests, builds a universal.appwithscripts/build-app.sh, signs and notarizes it, and attaches the zip to a GitHub release. Secrets:DEVELOPER_ID_P12(base64.p12),DEVELOPER_ID_P12_PASSWORD,NOTARY_KEY(base64 App Store Connect.p8),NOTARY_KEY_ID,NOTARY_ISSUER_ID. - Debug builds:
[DECANT_TOOL=base64] DECANT_INPUT=… [DECANT_AUX=…] DECANT_SNAPSHOT=out.png [DECANT_DARK=1] .build/debug/Decantwrites a PNG of the window and quits without touching history. UserDefaults can be set per run with launch arguments, e.g.-formatterTree YES.
MIT.