CMU Sphinx-4
Don’t want to install CMU Sphinx-4? Drop the file here.
The first 20 minutes of any recording are transcribed free: a recording up to 20 minutes transcribes in full, a longer one is previewed, and a pack from $6 (500 minutes) transcribes the rest and opens every export, and credits never expire.
The classic Java speech engine from CMU.
Best for legacy Java systems still on Sphinx. Pricing: free.
What it is
A pure-Java HMM/Gaussian-mixture engine. BSD-2-Clause.
Watch out for: Largely superseded; minimal recent commits.
Install / use
git clone https://github.com/cmusphinx/sphinx4What people actually do with CMU Sphinx-4-style transcription
The tool is the means. These are the jobs — each one priced at published rates, each one wired up on its own page.
Features
| Speaker diarization | No |
| Word-level timestamps | Yes |
| Streaming / real-time | Yes |
| Languages supported | 15 |
| HIPAA eligible | No |
Links
CMU Sphinx-4 vs Whipscribe
| Feature | CMU Sphinx-4 | Whipscribe |
|---|---|---|
| Category | Open source | Transcription APIs |
| Pricing | free | $6–$24 one-time packs (credits never expire) · first 20 minutes free |
| Speaker identification | No | Named in the summary, key quotes and chapters |
| Word timestamps | Yes | Yes |
| Streaming | Yes | No |
| Languages | 15 | 99 |
| Platforms | JVM | Web, API, MCP |
Alternatives to CMU Sphinx-4
Frequently asked about CMU Sphinx-4
Is CMU Sphinx-4 free?
Yes. CMU Sphinx-4 is free and open source.
Does CMU Sphinx-4 work on Mac, Windows and Linux?
CMU Sphinx-4 runs on JVM. It is not listed for other platforms; check the vendor for anything beyond JVM.
How do I install CMU Sphinx-4?
Clone and run it from source: `git clone https://github.com/cmusphinx/sphinx4`. Expect to install its dependencies yourself — the README has the exact steps per OS.
How many languages does CMU Sphinx-4 support?
CMU Sphinx-4 lists 15 languages.
Does CMU Sphinx-4 identify different speakers?
No. CMU Sphinx-4 does not label speakers; a conversation comes back as one continuous text. If you need speaker labels, that is a separate tool or a different service.
Does CMU Sphinx-4 give word-level timestamps?
Yes — CMU Sphinx-4 produces timing per word, which is what subtitle cues and clip boundaries need.
Can CMU Sphinx-4 transcribe live audio?
Yes — CMU Sphinx-4 supports streaming / live input, not just finished files.
Is CMU Sphinx-4 HIPAA compliant?
CMU Sphinx-4 does not claim HIPAA compliance. For PHI, run it on infrastructure you control or choose a service that will sign a BAA.
What are the limitations of CMU Sphinx-4?
Largely superseded; minimal recent commits.
Who is CMU Sphinx-4 best for?
Legacy Java systems still on Sphinx.
Does CMU Sphinx-4 run offline?
CMU Sphinx-4 runs on your own machine — it is open source, so nothing leaves the computer unless you configure it to.
Can I use CMU Sphinx-4 in the browser?
No — CMU Sphinx-4 is a JVM application, not a web app. You install it rather than sign in to it.
Where is the CMU Sphinx-4 source code?
On GitHub at github.com/cmusphinx/sphinx4.
What kind of tool is CMU Sphinx-4?
In this directory CMU Sphinx-4 is filed under toolkit, framework, legacy as a open-source tool.
What are the alternatives to CMU Sphinx-4?
There is a side-by-side page at /tools/sphinx4-alternatives comparing CMU Sphinx-4 with the closest tools in the same category on price, platform and features.
Whipscribe is a hosted transcription service. If you want transcripts without running infrastructure, paste a URL or drop a file in the form below — you'll have a transcript in seconds.
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