# julius-speech/julius

Open-Source Large Vocabulary Continuous Speech Recognition Engine

Repository: https://github.com/julius-speech/julius
Canonical: https://ross.abutalabs.com/products/julius-speech-julius
Language: C
License: BSD-3-Clause
License Family: permissive
Topics: speech, recognition, audio-processing, speech-recognition
Last push: 2025-06-16T07:10:03+00:00

## Health v2 (maintenance only)
Score: 35/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 27, release rhythm 8, longevity 100
- inputs: {"age_days": 4146, "days_push": 443, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1933, forks 304 (observed 2026-08-28T04:05:56.384663+00:00)

## What it is
Julius is an open-source large vocabulary continuous speech recognition (LVCSR) decoder written in C, based on word N-gram language models and context-dependent HMM acoustic models with a 2-pass tree-trellis search. It supports real-time decoding on devices from microcontrollers to cloud servers, DNN-based decoding, and multi-instance recognition, with model compatibility with HTK and SRILM formats.

## Use cases
- transcribe japanese speech to text offline
- run speech recognition on embedded low-memory devices
- decode large vocabulary dictation in real time
- recognize speech using custom grammar or word lists
- experiment with HMM and DNN acoustic models for ASR
- build a voice command recognizer for a robot

## When to choose
- you need a small-footprint, self-contained ASR engine in C
- you have HTK/ARPA format acoustic and language models
- you target Linux, Windows, Mac, or Android including embedded devices
- you need grammar-based or isolated-word recognition alongside dictation

## When to avoid
- you want a modern pretrained end-to-end model like Whisper out of the box
- you need cloud-scale accuracy on many languages without training your own models
- you prefer Python-first tooling and ecosystems

## Facets
- artifact type: library
- maturity: maintenance
- function: speech-recognition, audio-processing, nlp
- domain: speech-processing, machine-learning
- platform: windows, cross-platform, cli
- tags: lvcsr, hmm, dnn-decoding, japanese, asr, c, natural-language-processing, linux, macos, android

## Member repositories
- julius-speech/julius (main) score 35

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:56.384663+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T03:08:34.252716+00:00, confidence not recorded.
  - readme: https://github.com/julius-speech/julius (fetched 2026-08-28T04:05:56.384663+00:00, sha 22b2ad6418fa)
- Data as of 2026-08-30T08:39:29.467469+00:00.