SentencePiece

by Google

Subword tokenizer used by Whisper, SeamlessM4T, Canary.

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TL;DR

Best for building/fine-tuning ASR tokenizers without external tools. Pricing: free.

Category
Open source
License
Apache-2.0
Stars
★ 12.0k
Last push
2026-08-07
Pricing
free
Platforms
Linux, macOS, Windows

What it is

Google's reference subword tokenizer. Apache-2.0.

Best for: Building/fine-tuning ASR tokenizers without external tools.
Watch out for: Bytes-only by default; check sample rate compatibility.

Install / use

pip install sentencepiece

Features

Speaker diarizationNo
Word-level timestampsYes
Streaming / real-timeNo
Languages supported99
HIPAA eligibleNo

Links

GitHub repo ↗

SentencePiece vs Whipscribe

FeatureSentencePieceWhipscribe
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
Languages9999
PlatformsLinux, macOS, WindowsWeb, API, MCP

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