🌱 Renamr

⬇️ Download Renamr for macOS

Rename a whole folder by example. Correct one filename, hit enter, and every other file transforms by the same inferred logic — date reformatting, field reordering, dropped tokens, re-casing, renumbering, and all. No regex, no field chips, no template language. Free, open source, and 100% on your Mac.

It's FlashFill's interaction applied to filenames — a domain spreadsheets can't reach.

DSC0931.JPG                                  →   Beach 1.jpg          (rename one…
DSC0942.JPG                                  →   Beach 2.jpg           …the rest follow)
PXL_20240115_103045.jpg                      →   2024-01-15.jpg
Screenshot 2026-05-29 at 7.18.42 PM.png      →   2026-05-29 Screenshot.png
01 - Daft Punk - Get Lucky.mp3               →   01 Get Lucky.mp3

You demonstrate the result once. Renamr infers the rule and previews it across the folder.

• Free & open source (MIT)
• 100% local — your files never leave your Mac, no account, no network
• Native macOS (Swift) — small, fast, no Electron

How it works

The moat is a path-aware programming-by-example synthesizer (RenamrCore), not a rule builder:

1. Tokenizer — each filename is parsed into typed segments (dates, counters, words, separators) instead of raw characters. Dates are recognized across formats and carved out as single tokens; DSC0931 splits into word DSC + number 0931. Generalization happens over "the 1st date" / "the 3rd word", which is what lets one example teach the whole folder.
2. Synthesizer — for each token of your corrected name, it enumerates every way an input token could explain it (copy / re-case / date-reformat / number-repad) plus a literal fallback, then picks the cheapest under a simplicity prior: copying real data beats hard-coding a literal, while separators fall through to literals. That bias is the "it just knew" behaviour.
3. Apply — the learned program runs over every file by re-parsing and re-emitting (so 20240115 → 2024-01-15 generalizes to 20240116 → 2024-01-16). Files missing a referenced field are flagged, never silently mangled.

See PLAN.md for the roadmap (version-space search, disagreement loop, the AppKit/SwiftUI app, signing & distribution).

Status

Working v0.1 — native SwiftUI app (Renamr.app), a CLI (renamr), and the engine, with a 24-case test suite plus a 160-scenario benchmark (swift run renamr-corpus Tests/Fixtures/corpus-benchmark.json). Handles dates (many layouts incl. month names), times, counters (pad/strip/renumber), reordering, dropping, re-casing, variable-length titles, separator/case normalization, and per-file extensions. When it isn't sure, it flags — it never silently mangles a file.

Install

1. Download Renamr.dmg from the Releases page.
2. Open it and drag Renamr to Applications.

First launch (one time)

Renamr is free and open source but not notarized by Apple, so the first launch needs one extra step (this is normal for indie/OSS Mac apps):

• Double-click Renamr. macOS says it "could not verify" the app — click Done (not Move to Trash).
• Open System Settings ▸ Privacy & Security, scroll to Security, and click Open Anyway next to Renamr, then confirm.
• It opens normally from then on.

Power-user shortcut instead of the above:

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

Build from source

Requires Xcode (or Swift 6 Command Line Tools).

swift test                       # run the engine test suite
swift run renamr "DSC0931.JPG" "Beach 1.jpg" *.JPG   # CLI preview (✓ confident, ? flagged)
./Scripts/package-app.sh         # build Renamr.app (ad-hoc signed, local use)
./Scripts/build-dmg.sh           # build a distributable Renamr-<version>.dmg

Project layout

Sources/RenamrCore/   the synthesizer engine (pure Swift + Foundation, no UI)
Sources/renamr/       a thin CLI that exercises the engine
Tests/                XCTest suite

License

MIT — see LICENSE.