Vosk vs WhisperX
Both are alternatives to Deepgram. Here's how they stack up — verified facts, no spin.
Also searched as WhisperX vs Vosk — same comparison, one verdict.
Vosk and WhisperX are closely matched on ownership (95 vs 90) — this one comes down to pricing and to which trade-offs below you can live with.
Vosk
Real-time transcription on a CPU. Runs on a Raspberry Pi.
Vosk is a lightweight offline speech-recognition toolkit built for constrained environments — it runs in real time on a CPU, works on Android, iOS and single-board computers, and its models are tens of megabytes rather than gigabytes. It will not match Whisper on accuracy for difficult audio. It is the right answer when you need speech recognition on a device, offline, with no GPU and no network, which is a requirement no managed API can satisfy at any price. Apache-2.0.
WhisperX
Accurate word timestamps and speaker labels — Whisper's two weak spots, fixed.
WhisperX wraps Whisper with forced phoneme alignment to produce genuinely accurate word-level timestamps, and adds speaker diarization so output is attributed by speaker. Those are precisely the two things plain Whisper does poorly and the two things a managed API is usually bought for. If your product needs subtitles that land on the word, or meeting transcripts that say who spoke, this closes the gap. BSD-2-Clause, though note the diarization component it uses carries its own model terms worth checking.
Side by side
6 points of comparison, every one read from a verified field. Green marks the side that wins a row outright. A dash means we do not hold that fact — never that it is zero.
| Vosk | WhisperX | |
|---|---|---|
| Sovereignty ScoreOur transparent 0–100 composite for data ownership and exit cost. | 95 | 90 |
| Open source | Yes | Yes |
| Self-hostable | Yes | Yes |
| Local-first data | Yes | Yes |
| License | Apache-2.0 | BSD-2-Clause |
| Pricing | Free, Apache-2.0. | Free. Diarization models may require accepting separate terms. |
Vosk edges it on the Sovereignty Score, but the right pick depends on the trade-offs below.
Weighing both against staying on Deepgram? Is Deepgram free? What it actually costs →
Vosk
Strengths
- +Real-time on CPU — no GPU required at all
- +Tiny models; runs on phones and single-board computers
- +Fully offline, which some products require by law
- +Around twenty languages supported
Trade-offs
- −Noticeably less accurate than Whisper on hard audio
- −Smaller language coverage
- −No built-in diarization
WhisperX
Strengths
- +Word-level timestamps accurate enough for subtitles
- +Speaker diarization included in the pipeline
- +Batched inference makes it fast on long recordings
- +BSD-2-Clause
Trade-offs
- −Diarization models have their own licence terms to review
- −More moving parts than faster-whisper alone
- −Heavier GPU memory requirement with diarization enabled
Which one fits you
The trade-offs above, turned into a decision. Find the line that describes your team.
Choose Vosk
if a lower exit cost matters more to you than any single feature, and real-time on CPU — no GPU required at all.
Choose WhisperX
if word-level timestamps accurate enough for subtitles.
Neither, yet
if both carry a real cost you should weigh first — noticeably less accurate than Whisper on hard audio, and diarization models have their own licence terms to review. If either of those is a dealbreaker for your team, the shortlist is wrong rather than the choice.
Vosk vs WhisperX — common questions
Is Vosk a better fit than WhisperX for speech recognition & transcription?
It depends on what you are optimising for, and the honest split is this: Vosk scores 95 to WhisperX's 90 on data ownership and exit cost, so it is the safer choice if you care about being able to leave. WhisperX earns its place on a different axis — word-level timestamps accurate enough for subtitles. Neither is a wrong answer for every team; the table above is the actual comparison.
What happens if we want to switch later?
Vosk keeps its data local or in open formats, so leaving is an export rather than a negotiation. WhisperX is still self-hostable, so the files stay on your server either way — but it is not local-first by design, so check what its export produces before you rely on it.
Can I self-host Vosk or WhisperX?
Both can be self-hosted. The difference is what it costs you in time rather than whether it is possible — see the setup and maintenance rows above.
Are Vosk and WhisperX both alternatives to Deepgram?
Yes — both appear in our Deepgram comparison, which is why they are worth putting side by side. People usually arrive here already having decided to move off Deepgram and now choosing between the two replacements, which is a narrower and much easier question.
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Facts verified 2026-08-11. Licenses and pricing change — spotted something out of date? That's a correction we want.