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 |
| 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 |
| Text | Diff (side by side / unified, word highlights, folding), 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.
- 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. - 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.