fstalign

by Rev.com

Rev.com's WER + alignment scoring tool over WFSTs.

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TL;DR

Best for computing WER with formal/informal-equivalence tables. Pricing: free.

Category
Open source
License
Apache-2.0
Stars
★ 169
Last push
2026-05-12
Pricing
free
Platforms
Linux, macOS

What it is

A C++ tool that aligns hypothesis + reference via WFST and produces detailed error reports. Apache-2.0.

Best for: Computing WER with formal/informal-equivalence tables.
Watch out for: C++ tool only; learning curve.

Install / use

git clone https://github.com/revdotcom/fstalign

Features

Speaker diarizationNo
Word-level timestampsYes
Streaming / real-timeNo
Languages supported1
HIPAA eligibleNo

Links

GitHub repo ↗

fstalign vs Whipscribe

FeaturefstalignWhipscribe
CategoryOpen sourceTranscription APIs
Pricingfree$4–$24 one-time packs (credits never expire) · $2 single unlock · 60 min free on signup
Speaker diarizationNoYes
Word timestampsYesYes
StreamingNoNo
Languages199
PlatformsLinux, macOSWeb, API, MCP

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