JamCrate beta

Landing page, distribution and beta releases for the JamCrate macOS app.

JamCrate keeps your backing tracks, tabs and chord sheets in one place, on the Mac, offline. Pick a song and play: every track sits at the same level, the solo you marked loops in one click, the sheet is already open beside it, and your guitar processor switches to the right preset on its own as the song goes by.

Free during beta. No account, no cloud, no subscription. Your files stay yours, in a folder you can open in the Finder.

What it does

• Library — drop files or a folder anywhere in the window, or press ⌘I. What is unambiguous imports straight away; what is not goes to a short review that names the real problem: a tab with no song, a possible duplicate, an unreadable name. Files are copied into a library you own, at ~/Music/JamCrate/<Band>/<Song>/. Renaming moves the files with the name, deleting sends them to the Trash.
• Player — markers on the waveform, a solo looped in one click. Frags plays only the fragments you marked and skips the gaps, Loop repeats the track or the fragments. Tempo slows from 100% down to 50% with the pitch preserved — there is no speed-up and no separate pitch shift. Every track is level-matched on import, so changing songs does not move the volume knob.
• Tabs — PDF, plain text, ChordPro and Guitar Pro 3/4/5 open beside the transport. GP files are drawn as an aligned monospace grid, one track at a time. Auto-scroll follows playback, zoom runs 70–240%. This is a reader: GP playback is not in scope, and effects, bends, slides and lyrics are not drawn.
• Setlists — a numbered list per set, with Auto-next: the track ends, the next one starts, and after the last it stops honestly.
• Sharing — your markers and tone assignments live in song.jamc.json beside your own files and contain no audio, so passing that file to a friend is legal.
• Backups — ⇧⌘B writes a .jamcrate.zip of the library into Backups/; every backup is its own timestamped file, so the folder is the version history. Restore merges and never overwrites.
• Languages — English, Russian and German.

Presets and MIDI

A preset is a .jamrig file — a folder with a rig.json in it, living in ~/Music/JamCrate/Rigs/. It is data, not code: which device names to match, the MIDI channel, and a list of tones, each one a sequence of MIDI messages. Adding a device means adding a file; rigs can be passed around. Open the Rig window with ⌥⌘R to see profiles, connection status and a Test button on every tone.

• M-VAVE Tank-G — verified on the pedal itself: banks 1–9 × slots A–D over plain USB, with no vendor app running.
• The rest of the M-VAVE family — Tank-B, Tank-Mini, Tank-Pro, Blackbox, Hush, KE1, KPT Pro, MK20, MK300, SK17. These ship so their owners have something to try rather than nothing, and none of them is verified.
• Line 6 (Helix / Stadium, HX Stomp and Stomp XL, HX Effects) and Boss GT-1000 / GT-1000CORE — the frames come from the makers' own MIDI documentation, and the names say (documented) on purpose: that is a claim about where the frames came from, not about your pedal.
• Anything else — describe it in a .jamrig and it works: program change, control change and SysEx are all supported.

Give a tone to a marker and it sounds from that point on; a default tone covers the rest of the song. While playing, the message is fired as the playhead crosses the marker, with a short lookahead and a quarter-second debounce.

The honest part. A wrong frame fails silently — CoreMIDI reports success and the pedal ignores it. So press Test on a preset. If the pedal switches, that profile works and the rest of it should too. If nothing happens, send the model name and which preset you pressed to beta@jamcrate.app; that one line is usually enough to derive the frame.

Install

Free beta. macOS 14 Sonoma or later, Apple Silicon and Intel, signed and notarized — so macOS opens it with an ordinary double-click.

• brew install --cask vitas/jamcrate/jamcrate, later brew upgrade --cask jamcrate
• Or the newest release's JamCrate.dmg (about 20 MB), same result.
• Install notes shipped inside the DMG: DIST_README-notarized.md for signed builds, DIST_README.md for the ad-hoc fallback.
• Nothing to install: https://play.jamcrate.app — the browser player, demo set included.

Links

• Site: https://jamcrate.app
• Feedback: Telegram https://t.me/jamcrate (mostly Russian), GitHub Discussions https://github.com/vitas/jamcrate-beta/discussions (English), beta@jamcrate.app

This repository holds the public site source, the release assets and the cask; the app itself is closed source.