Choosing a Deepgram alternative realtime speech API usually comes down to one question: do you need raw streaming speech-to-text, or live captions that already include translation, speakers, and minutes on a single connection?
Quick verdict: Deepgram is often the better pick when you only need high-quality streaming STT (and you are comfortable stacking add-ons or a separate machine-translation service). LecSync Realtime STT fits when you want transcription plus live translation, speaker labels, structured digest minutes, glossary, and optional 30-day storage billed at one flat $0.01 per audio minute—no per-feature line items.
What is a realtime speech API with built-in translation?
A realtime speech API with built-in translation accepts live audio over a streaming connection and returns interim then final transcripts together with target-language text on that same session—without you wiring a separate machine-translation hop. Direction can follow each segment; a third language that appears mid-call still maps into your chosen target. LecSync documents this as one WebSocket with transcription and translation paired server-side (developers).
Side-by-side: LecSync vs Deepgram realtime STT
Figures below are from each vendor’s public pages (checked ~2026-09-30). They are product claims or list prices, not an independent bake-off.
| Dimension | LecSync Realtime STT | Deepgram (public pricing / STT) |
|---|---|---|
| Connection model | One WebSocket: transcription + translation | Live STT WebSocket (listen streaming); MT typically separate if you need live captions in another language |
| First word on screen | 0.28 s after speech starts (public product figure) | Not published as a single comparable “first word” number on the pricing page |
| Live translation | Any-to-any among 60 languages; ~88 ms added to first translation token | Public STT pricing lists transcription features/add-ons, not built-in realtime MT on the STT stream |
| Speakers | Labels on final segments when speakers enabled, with timestamps | Streaming speaker diarization is a PAYG add-on ($0.0020/min); pre-recorded diarization listed as included |
| Digest / minutes | digest:true → structured minutes on the same connection | Audio Intelligence summarization billed per token separately (e.g. Summarization $0.0003/1k in / $0.0006/1k out PAYG)—not the same as digest-on-same-WS |
| Backlog under hitch | Cap 2 s; captions catch the current sentence within ~1 s after recovery | Not described the same way on the public pricing page |
| Regions | 5 gateways: dal, hz, jp2, ru, uk | EU residency endpoint mentioned (api.eu.deepgram.com) among compliance options |
| Pricing shape | Flat $0.01 / audio minute, all listed features included | Base streaming STT + optional add-ons; Free $200 credit on pricing page |
Sources: LecSync developers, Deepgram pricing.
When to pick Deepgram
Pick Deepgram when your product is primarily English (or monolingual) streaming STT—voice agents, call analytics, or captioning where the UI language matches the audio. Nova-3 streaming PAYG list prices (promotional / regular on the public page) are lower than LecSync’s flat rate for transcription alone:
- Nova-3 Monolingual streaming: $0.0048/min current promo; $0.0077/min regular
- Nova-3 Multilingual streaming: $0.0058/min promo; $0.0092/min regular
Nova models are described as supporting 45+ languages with multilingual/code-switch capabilities for transcription. Streaming add-ons (PAYG) include speaker diarization, keyterm prompting, redaction, and entity detection; smart formatting is included. If you only need that stack—and you will add your own MT later or never translate—Deepgram’s meter can stay cheaper. A Free $200 credit lowers the cost of a first prototype (Deepgram pricing).
When to pick LecSync
Pick LecSync when the product requirement is live bilingual (or any-to-any) captions, not just a transcript string. Typical integrations:
- Classroom or webinar clients that show source + target lines as people speak
- Cross-border meetings where speaker turns must stay labelled while text is translated
- Apps that want structured minutes (
digest) without standing up a second summarization pipeline - Teams that prefer one invoice line: transcription, translation, timestamps, speakers, glossary, AI translation polish, digest, and optional
store:true(recording + transcript JSON for 30 days)
Connect with POST https://api.lecsync.com/v1/realtime/connect and a Bearer key, then stream on the returned WebSocket (developers). Preview text streams, then finals; language auto-detect is available. Disabling features does not lower the $0.01 rate; enabling all of them does not raise it.
Pricing worked example (public list rates)
Assume 60 minutes of streaming audio, Pay As You Go, and you need speaker labels. Deepgram rates below are from the public pricing page (~2026-09-30); promotional rows are labelled.
| Stack | Rate (per audio min) | 60 min estimate |
|---|---|---|
| Deepgram Nova-3 Monolingual streaming (promo) + streaming diarization | $0.0048 + $0.0020 = $0.0068 | $0.41 |
| Same stack at regular STT list | $0.0077 + $0.0020 = $0.0097 | $0.58 |
| Deepgram Nova-3 Monolingual (promo) + diarization + keyterm | $0.0048 + $0.0020 + $0.0013 = $0.0081 | $0.49 |
| Same at regular STT + those add-ons | $0.0077 + $0.0020 + $0.0013 = $0.0110 | $0.66 |
| LecSync all-in (STT + translation + speakers + digest + glossary + polish + optional 30-day store) | $0.01 | $0.60 |
Deepgram can win on dollars for raw streaming STT + diarization alone—especially under the current streaming promo. Once you need live translation on the same path, you typically stitch STT to a separate MT service (extra latency, keys, and billing). LecSync’s $0.01 figure already includes that translation path plus digest and glossary on one connection. LecSync rounds each stream up to whole audio minutes; reconnect starts a new stream; no accepted audio means no charge.
Integration scenarios
Live classroom captions. Students hear English (or mixed languages); the UI shows a target language line without you operating a second vendor. LecSync’s per-segment direction and third-language → target behavior match that layout.
Meeting client with speaker rails. Both vendors can label speakers. On Deepgram streaming, diarization is an add-on; on LecSync it is inside the flat minute. LecSync also returns audio-aligned startMs for jump-to-playback.
Agent that only needs English ASR. Deepgram Flux / Nova streaming plus a Free credit is a natural starting point; you do not pay LecSync’s all-in rate for features you will never turn on.
FAQ
Is LecSync cheaper than Deepgram for realtime STT?
Not always. For streaming transcription alone, Deepgram’s public Nova-3 PAYG rates (promotional and regular) are lower than LecSync’s $0.01 flat minute. LecSync becomes competitive when you need live translation, speakers, digest minutes, glossary, and storage on one bill—features that would otherwise be add-ons or a second MT vendor.
Does Deepgram include realtime speech translation on the STT stream?
Deepgram’s public Speech-to-Text pricing lists transcription models and streaming add-ons such as diarization and keyterm prompting—not built-in realtime machine translation on that STT stream. For live captions plus translation, teams typically combine STT with a separate MT service. Confirm any newer product bundles on Deepgram’s own site before you design.
How fast is LecSync’s first caption word?
LecSync’s public developers page states the first word reaches the screen 0.28 seconds after speech starts, and that translation adds about 88 ms to the first translation token. Treat those as vendor-published product figures, not an independent lab benchmark against Deepgram.
What happens to LecSync latency after a network hitch?
Server-side audio backlog is capped at 2 seconds; audio beyond the cap is discarded rather than queued forever. After the hitch, captions are described as catching the current sentence within about 1 second, so delay does not keep stacking.
How do you start a LecSync realtime session?
Create a session with POST https://api.lecsync.com/v1/realtime/connect using a Bearer API key and your audio/transcribe JSON, then open the returned WebSocket URL and token. Curl, JavaScript, and Python samples are on the developers page.
Does turning features off make LecSync cheaper?
No. The public price is $0.01 per audio minute with listed features included. Disabling translation, speakers, or digest does not reduce the rate; enabling all of them does not increase it. Billing rounds each stream up to whole minutes.
Verdict
Use Deepgram when streaming STT (optionally with diarization and keyterms) is the whole job and you want the lowest public STT meter—or a $200 Free credit to explore. Use LecSync when your product brief says live translation, speaker-labelled finals, and digest minutes must arrive on one WebSocket at a predictable all-in minute price. Start with the LecSync Realtime STT docs and compare line items against Deepgram’s pricing page for your exact feature set.