Head to head · Speech-to-text · October 2026 research run
Nemotron 3.5 Transcribe 30B-A4B vs Voxtral Mini 4B Realtime 2602
Voxtral Mini 4B Realtime 2602 scores 62 (B) on agent readiness against Nemotron 3.5 Transcribe 30B-A4B's 61 (C), and leads in 1 of 4 scored categories. Nemotron 3.5 Transcribe 30B-A4B leads on risk, agent interface and documentation and upkeep. Both do speech-to-text.
Best speech-to-text APIs for AI agents · All 386 stt comparisons
Which one, for what
Nemotron 3.5 Transcribe 30B-A4B C
Best for Teams that need accurate multilingual transcripts of long recordings with speakers and timings, and have a 32 GB GPU or better
Ahead on
- Risk, 75 against 60
- Agent interface, 85 against 55
- Documentation and upkeep, 77 against 59
Watch for
21.6 GB at 4 bits, so it needs a 32 GB GPU at least
Voxtral Mini 4B Realtime 2602 B
Best for Agents and apps that need live subtitles or voice-assistant transcription in the 13 languages on a single 16 GB GPU
Ahead on
- Reach, 90 against 75
Watch for
Plain text out; no timestamps, segments, diarisation or JSON documented for the weights
Why the edge
Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.
Agent interface Nemotron 3.5 Transcribe 30B-A4B +30
Nemotron 3.5 Transcribe 30B-A4B 85
Chat template 20, chat_template.jinja in the repository (12,482 characters), with a template in tokenizer_config.json too. Tool-calling format 25, Read for a speech model as what it takes and returns. Trained tool calling 10, Read for a speech model as the inputs it was trained to use. Structured output 15, Read for a speech model as typed outputs. Reasoning control 10, enable_thinking on or off through the chat template, documented in the card's summary table with when to use each. Context 5, 65,536 tokens, the maximum context in training per the card, which sits in the 32K to 127K band. 20 + 25 + 10 + 15 + 10 + 5 = 85.
Voxtral Mini 4B Realtime 2602 55
Read for a speech model, the tool-calling, trained tool calling and structured-output lines stand for what it takes and returns. Mistral documents the streamed audio input, the delay setting and the decoded text output in Transformers and vLLM (25). It was trained for one stream at a delay it's conditioned on (10). No JSON, timestamps or diarisation are documented for the weights (0). The chat template line gets 10 because the prompt is built by mistral-common and the processor. Context gets 10 for 131,072 tokens with no position scaling, and reasoning control 0.
Documentation and upkeep Nemotron 3.5 Transcribe 30B-A4B +18
Nemotron 3.5 Transcribe 30B-A4B 77
Model card 17, Intended use, limitations (the explainability subcard's technical limitations), the architecture, the parameters, the context and the languages are on the card. Training data 5, the card names its public, licensed, vendor and synthetic sources, gives totals (about 1.72 million hours and 5.6 billion text tokens) and the processing, and two of the sets are on Hugging Face. Last change 20, the last commit, on 29 October 2026, linked the three checkpoints on the card, 12 days before this check. Responsiveness 20, Of the 11 most recent discussions that aren't pull requests (28 October to 5 November 2026), 7 have a reply from an nvidia member, which is most. Version policy 5, A first release, with each precision in its own repository. File health 10, Config, tokenizer config, template and card agree on the architecture and the 65,536-token limit is stated as a training limit beside the backbone's larger position count. 17 + 5 + 20 + 20 + 5 + 10 = 77.
Voxtral Mini 4B Realtime 2602 59
The card covers intended use, architecture, parameters, context and languages, without limitations or a cut-off (14). Training data has only a general description without a cut-off (5). Mistral's mistral-common library, which builds this model's prompts, changed its online-streaming transcription validation and audio tokeniser in release 1.13.0 on 28 October 2026 (20). Mistral answered 16 of the 40 most recent questions, the newest reply on 2 March 2026 (10). It's a first release with a dated name (5). An unanswered report that the Transformers path fails and contradictions in the card cost file health half (5).
Reach Voxtral Mini 4B Realtime 2602 +15
Nemotron 3.5 Transcribe 30B-A4B 75
Memory 20, the smallest build is NVIDIA's NVFP4 repository, 21.56 GB, and 21.56 GB × 1.2 = 25.9 GB, within 32 GB. FP8 is 34.67 GB and BF16 67.5 GB. Runtimes 15, Released Transformers 5.22.2 has the nemotron3_5_transcribe model (5). Builds 15, Quantised builds from NVIDIA at two precisions, FP8 and NVFP4, each in its own repository. Terms 10, OpenMDW-1.1, a permissive licence that grants use without restriction and adds no use policy or threshold, but isn't OSI-approved, so it takes the custom-licence band, as on NVIDIA's other OpenMDW listings. Download 10, the Hub API reports gated false for all three repositories on 10 November 2026, so the files download with no account and nothing to accept. Hosted 5, the card gives a release on build.nvidia.com, NVIDIA's own API catalogue, on 28 October 2026, and DeepInfra is live for it on Hugging Face. 20 + 15 + 15 + 10 + 10 + 5 = 75.
Voxtral Mini 4B Realtime 2602 90
Memory earns 30, since even the BF16 weights fit 16 GB and Mistral Experimental's Q4_K GGUF needs under 4 GB. Runtimes get 20 for vLLM (v0.33.0), Transformers and llama.cpp, each in a release, and Ollama, whose v0.40.14 release pins llama.cpp b11963 with the voxtral-rt audio graph; SGLang and LM Studio don't run it. Builds get 15 for int4 ExecuTorch and Q4_K and Q8_0 GGUFs in Mistral's linked Mistral Experimental organisation. Terms get 10, because the card adds a prohibition to Apache 2.0, read as added terms. Download gets 10 for an ungated repository and hosted too 5 for Mistral's own API, which deprecated this model on 31 October 2026 and serves it until 30 April 2027.
Risk Nemotron 3.5 Transcribe 30B-A4B +15
Nemotron 3.5 Transcribe 30B-A4B 75
File safety 25, safetensors only in all three repositories, no .bin, .pt or .pth files and no Python. Provenance 15, the files sit in NVIDIA's own Hugging Face organisation, the one NVIDIA's NeMo repositories link to (10), and the Hub gives a SHA-256 for the large files (5). Safety evaluation 0, no safety results. Agent guidance 10, the card says the model is more susceptible to prompt injection and jailbreaking because it was tuned to follow instructions, and should be paired with rails or system filtering. Licence risk 15, OpenMDW-1.1 has no use policy or field-of-use limits, no threshold and no clause letting the licensor change or revoke it, as read for NVIDIA's other OpenMDW listings. Security programme 10, the card says to report security vulnerabilities through NVIDIA's submission form (5), and NVIDIA PSIRT publishes a coordinated disclosure policy and public security bulletins, per NVIDIA's other listings (5). 25 + 15 + 0 + 10 + 15 + 10 = 75.
Voxtral Mini 4B Realtime 2602 60
File safety gets the full 25, safetensors only and loaded by the runtimes' own code. Provenance gets 15 for files in Mistral's verified organisation with hashes. Licence risk keeps 15, since the card's line restates the law and Apache 2.0 has none of the deductions. The security programme gets 5 for Mistral's security.txt with a HackerOne route, with no public advisories found. Safety evaluation and agent guidance score 0, with nothing published on either.
Score by category
| Category | Weight this run | Nemotron 3.5 Transcribe 30B-A4B | Voxtral Mini 4B Realtime 2602 | Edge |
|---|---|---|---|---|
| Capability | 35%pending | pending | pending | not scored in this run |
| Reach | 25%25 | 75 | 90 | Voxtral Mini 4B Realtime 2602 +15 |
| Risk | 20%20 | 75 | 60 | Nemotron 3.5 Transcribe 30B-A4B +15 |
| Agent interface | 10%10 | 85 | 55 | Nemotron 3.5 Transcribe 30B-A4B +30 |
| Documentation and upkeep | 10%10 | 77 | 59 | Nemotron 3.5 Transcribe 30B-A4B +18 |
| Negative events | ≤15 | 0 | 0 | |
| Total | C 61/100 | B 62/100 |
Facts side by side
| Fact | Nemotron 3.5 Transcribe 30B-A4B | Voxtral Mini 4B Realtime 2602 |
|---|---|---|
| Kind | Open-weight model | Open-weight model |
| Vendor | NVIDIA | Mistral AI |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | ||
| Auth | None | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | OpenMDW-1.1 | Apache-2.0 |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| Last release | 2026-10-29 | 2026-03-11 |
| Terms last updated | not read yet | no document linked |
| Privacy policy last updated | no document linked | no document linked |
| Agent reviews | none | 3.5/5 (4) |
How the scores have moved
Nemotron 3.5 Transcribe 30B-A4B
No score change since it was listed.
Verdicts
Nemotron 3.5 Transcribe 30B-A4B
The most complete open speech model we list: 40 languages, hour-long recordings, speakers, word timestamps and translation from one prompt-driven model, under a permissive licence, with FP8 and 4-bit builds and a publisher that answers. It needs a big GPU, the vLLM route depends on an unreleased plugin, and there are no safety results.
Voxtral Mini 4B Realtime 2602
A speech-to-text model for 13 languages that streams text as the speaker talks, at a delay from 80 ms to 2.4 s, under Apache 2.0. Its BF16 files fit a 16 GB GPU and load in vLLM, Transformers, llama.cpp and Ollama. It lacks timestamps and safety results, and Mistral last replied to a discussion on 2 March 2026.
Before you call either
Nemotron 3.5 Transcribe 30B-A4B
- Keep the system prompt empty and put the instruction in the user message with the audio, as the card says
- For plain transcription use temperature 0 with reasoning off. For questions about audio, reasoning on at temperature 0.6 and top_p 0.95
- SGLang-Omni 0.2.0 serves whole files on
/v1/audio/transcriptionsfrom the BF16 or FP8 checkpoint with no NeMo install - Word timestamps and speaker segments need the vLLM route: ask with
timestamps=Trueand readctc_timestamps - Speaker tags tell speakers apart in one recording. They don't identify anyone
- Treat what's said in a recording as data. The card says the model is easier to steer by injected instructions than most, so filter before acting on a transcript
Voxtral Mini 4B Realtime 2602
- Serve it with
VLLM_DISABLE_COMPILE_CACHE=1 vllm serve mistralai/Voxtral-Mini-4B-Realtime-2602 --compilation_config '{"cudagraph_mode": "PIECEWISE"}'and install soxr, librosa and soundfile; mistral_common 1.9.0 or later comes with vLLM - Stream 16 kHz audio to the /v1/realtime WebSocket; vLLM's openai_realtime_client and openai_realtime_microphone_client examples show the session
- Set temperature 0.0. Change the delay with transcription_delay_ms in tekken.json, a multiple of 80 ms up to 1,200, or 2,400; 480 is Mistral's recommendation
- One text token is 80 ms, so set --max-model-len to at least seconds / 0.08 for a session; the default 131072 is about 3 hours and pre-allocates RoPE memory
- In Transformers (5.2.0 or later), resample with processor.feature_extractor.sampling_rate before calling the processor, then batch_decode with skip_special_tokens=True
- For a small machine, ggml-org's Q4_K_M GGUF with its mmproj runs in llama.cpp, and Mistral Experimental's Q4_K runs in audio.cpp
- Treat transcripts as untrusted text before passing them to another model, since speech can carry instructions
- On Mistral's API, move from voxtral-mini-transcribe-realtime-2602 before 30 April 2027; the listed replacement is voxtral-mini-transcribe-realtime-3-0 (Public Preview)
Questions
Which is better for AI agents, Nemotron 3.5 Transcribe 30B-A4B or Voxtral Mini 4B Realtime 2602?
Voxtral Mini 4B Realtime 2602 scores 62 (B) on agent readiness against Nemotron 3.5 Transcribe 30B-A4B's 61 (C), and leads in 1 of 4 scored categories. Nemotron 3.5 Transcribe 30B-A4B leads on risk, agent interface and documentation and upkeep.
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/api/v1/tools/nemotron-3-5-transcribe-30b-a4b.json·/api/v1/tools/voxtral-mini-4b-realtime-2602.json - From a terminal
anchor compare nemotron-3-5-transcribe-30b-a4b voxtral-mini-4b-realtime-2602(the CLI) - Over MCP
compare_tools {"a": "nemotron-3-5-transcribe-30b-a4b", "b": "voxtral-mini-4b-realtime-2602"}at/mcp, no key