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Model infoModelsSnapshot: 15 Oct 2026

StepFun / StepAudio

StepAudio 2.5 ASR

Speech recognition with one-shot audio submission and incremental transcription output.

Transcription
availableClosed weightsSpeech-to-text
Official documentation (opens in a new tab)Reviewed 12 Oct 2026
8 of 18 specification fields collected
Context windowNot collectedAwaiting source review
Maximum outputNot collectedAwaiting source review
Input billingSee ratesStepFun China
Output billingSee ratesPublished units and conditions below

Specifications

Provider-documented facts. “Not collected” means we have not verified that field yet, not that the feature is unsupported.

Context / input limit
Not collected
Maximum output
Not collected
Input modalities
AudioSource for Input modalities (opens in a new tab)
Output modalities
TextSource for Output modalities (opens in a new tab)
Reasoning
Not collected
Tool calling
Not collected
Structured output
Not collected
Streaming
SupportedSource for Streaming (opens in a new tab)

SSE streams text after a complete audio submission; live audio input uses a separate WebSocket endpoint when listed.

Batch processing
Not collected
Fine-tuning
Not collected
Knowledge cutoff
Not collected
Release date
Not collected
Parameters
4BSource for Parameters (opens in a new tab)
Architecture
Multi-Token Prediction (MTP)Source for Architecture (opens in a new tab)
Languages
Chinese, EnglishSource for Languages (opens in a new tab)
Context caching
Not collected
Input audio format
OGG, MP3, WAV, PCM, M4ASource for Input audio format (opens in a new tab)
Snapshots and aliases
stepaudio-2.5-asr, stepaudio-2.5-asr-streamSource for Snapshots and aliases (opens in a new tab)

Two transport selectors for the same documented ASR family, not separate checkpoints.

Access & pricing

Prices belong to an endpoint and billing tier. A provider listing does not guarantee access for every account or region.

StepFun China

Provider source (opens in a new tab)
API model ID
stepaudio-2.5-asr
Access
StepFun account and regional API key required. Documented availability, not a paid inference verification.
Regions
China platform (.com); deployment geography and data residency are not established by the hostname.
API endpoint URL
POST https://api.stepfun.com/v1/audio/asr/sseSource for API endpoint URL (opens in a new tab)

Prices retain their published currencies and billing units below.

Published billing units · original currency · observed 12 Oct 2026
CategoryUsageRateUnit
Speech recognitionTranscription1CN¥0.15audio hour

Rate conditions

  1. Whole audio submitted once; text streamed via SSE. Live-stream rates differ where available.
Pricing source (opens in a new tab)

Data & enterprise terms

Retention, training use, regional processing and enterprise terms have not been summarized for this endpoint.

StepFun China

Provider source (opens in a new tab)
API model ID
stepaudio-2.5-asr-stream
Access
StepFun account and regional API key required. Documented availability, not a paid inference verification.
Regions
China platform (.com); deployment geography and data residency are not established by the hostname.
API endpoint URL
WSS wss://api.stepfun.com/v1/realtime/asr/streamSource for API endpoint URL (opens in a new tab)
Streaming mode
Bidirectional audio input and text output with VAD and word timing.Source for Streaming mode (opens in a new tab)

Prices retain their published currencies and billing units below.

Published billing units · original currency · observed 12 Oct 2026
CategoryUsageRateUnit
Speech recognitionLive transcription1CN¥1.20audio hour

Rate conditions

  1. Bidirectional WebSocket ASR; distinct from the one-shot SSE price.
Pricing source (opens in a new tab)

Data & enterprise terms

Retention, training use, regional processing and enterprise terms have not been summarized for this endpoint.

StepFun International

Provider source (opens in a new tab)
API model ID
stepaudio-2.5-asr
Access
StepFun account and regional API key required. Documented availability, not a paid inference verification.
Regions
International platform (.ai); deployment geography and data residency require account-specific confirmation.
API endpoint URL
POST https://api.stepfun.ai/v1/audio/asr/sseSource for API endpoint URL (opens in a new tab)
Languages
Chinese, English, Japanese (preview), Korean (preview), French (preview), Spanish (preview)Source for Languages (opens in a new tab)

The international API expands the language list beyond the model overview. Preview languages are not described as generally available.

Prices retain their published currencies and billing units below.

Published billing units · original currency · observed 12 Oct 2026
CategoryUsageRateUnit
Speech recognitionTranscription1$0.022audio hour

Rate conditions

  1. Whole audio submitted once; text streamed via SSE. Live-stream rates differ where available.
Pricing source (opens in a new tab)

Data & enterprise terms

Retention, training use, regional processing and enterprise terms have not been summarized for this endpoint.

StepFun International

Provider source (opens in a new tab)
API model ID
stepaudio-2.5-asr-stream
Access
StepFun account and regional API key required. Documented availability, not a paid inference verification.
Regions
International platform (.ai); deployment geography and data residency require account-specific confirmation.
API endpoint URL
WSS wss://api.stepfun.ai/v1/realtime/asr/streamSource for API endpoint URL (opens in a new tab)
Streaming mode
Bidirectional audio input and text output with VAD and word timing.Source for Streaming mode (opens in a new tab)

Prices retain their published currencies and billing units below.

Published billing units · original currency · observed 12 Oct 2026
CategoryUsageRateUnit
Speech recognitionLive transcription1$0.18audio hour

Rate conditions

  1. Bidirectional WebSocket ASR; distinct from the one-shot SSE price.
Pricing source (opens in a new tab)

Data & enterprise terms

Retention, training use, regional processing and enterprise terms have not been summarized for this endpoint.

Caching

Caching can reuse earlier input processing. Availability, lifetime and billing depend on the endpoint. A cache hit still generates a new response.

01 / INITIAL INPUTProcess & retain

The system processes eligible input and retains reusable state.

02 / LATER REQUESTCheck available state

Reuse depends on matching input, session state and the cache policy.

03 / CACHE HITReuse & generate

Reusing state can reduce repeated work. Any charges follow the billing rules below.

StepFun China

stepaudio-2.5-asr
Not verified
How it works
Not collected
Minimum reusable input
Not collected
Lifetime & refresh
Not collected
How to enable it
Not collected
Usage fields
Not collected
Billing rules
Not collected
Limits & data boundaries
Not collected

No verified cache rate for this endpoint. An empty rate is not a zero charge.

StepFun China

stepaudio-2.5-asr-stream
Not verified
How it works
Not collected
Minimum reusable input
Not collected
Lifetime & refresh
Not collected
How to enable it
Not collected
Usage fields
Not collected
Billing rules
Not collected
Limits & data boundaries
Not collected

No verified cache rate for this endpoint. An empty rate is not a zero charge.

StepFun International

stepaudio-2.5-asr
Not verified
How it works
Not collected
Minimum reusable input
Not collected
Lifetime & refresh
Not collected
How to enable it
Not collected
Usage fields
Not collected
Billing rules
Not collected
Limits & data boundaries
Not collected

No verified cache rate for this endpoint. An empty rate is not a zero charge.

StepFun International

stepaudio-2.5-asr-stream
Not verified
How it works
Not collected
Minimum reusable input
Not collected
Lifetime & refresh
Not collected
How to enable it
Not collected
Usage fields
Not collected
Billing rules
Not collected
Limits & data boundaries
Not collected

No verified cache rate for this endpoint. An empty rate is not a zero charge.

What the measurements say

No benchmark observations have been added for this model. We do not turn a vendor description into a performance score.

Latency and throughput depend on the host, request size, reasoning settings and load. There is no measured speed or global usage figure in this record.

The record behind the model

Why it is included

Inferred for this named native commercial service from official model/API documentation and comparison with StepFun’s public model repositories. No release of weights for this exact named service was found in the reviewed inventory. Public Step 3/3.5/3.7, Step-Audio Mini/R1/R1.1, Step1X and StepVideo releases are excluded; this does not assert that every StepFun model is closed.

Classification evidence (opens in a new tab)

Sources reviewed