StepFun
StepFun (阶跃星辰) is a Shanghai-based AI foundation-model company whose open platform serves the Step model family — multimodal reasoning (step-3.7-flash), fast language reasoning (step-3.5-flash), vision, image generation and editing (step-2x-large, step-image-edit-2), and a deep audio stack spanning TTS, voice cloning, ASR, and end-to-end realtime voice (StepAudio 2.5) — via an OpenAI-compatible REST API at api.stepfun.com, an Anthropic-compatible Messages API, WebSocket realtime channels, and a hosted StepSearch MCP server for agent clients.
StepFun is listed with 12 APIs on the APIs.io network, including Realtime API, and 11 more. Tagged areas include Artificial Intelligence, LLM, Multi-Modal, Chat Completions, and Audio.
The StepFun catalog on APIs.io includes 1 event-driven AsyncAPI specification.
StepFun’s developer surface includes engineering blog, documentation, API reference, getting-started guide, support, pricing, signup flow, and 20 more developer resources.
Kin Score
Markets this provider is in provisional
The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.
| Market | Position | Depth | Registered MCP server | Declares compatibility |
|---|---|---|---|---|
| AI Model Routing | covered | 19.7 (thin) | - | 1 |
| Obsidian Community Plugins (third-party APIs the Obsidian plugin ecosystem integrates) | covered | 19.7 (thin) | - | 1 |
Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.
Standards implemented 3
Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.
APIs 12
Individual APIs this provider publishes, each with its own machine-readable definition.
StepFun Chat Completions API
OpenAI-compatible chat completions for the Step model family (e.g. step-3.7-flash, step-3.5-flash, stepaudio-2.5-chat), with multimodal image/video/audio message parts, tool cal...
StepFun Messages API
Anthropic Messages API-compatible endpoint (POST /v1/messages) that lets the Anthropic SDK and Claude-style JSON structures run against Step models by pointing base_url at https...
StepFun Responses API
OpenAI Responses API-style endpoint for generating model responses on the StepFun open platform.
StepFun Models API
List available Step models, retrieve a single model, and inspect the model object.
StepFun Audio API
Speech synthesis (TTS), voice cloning with preview, official voice catalog, audio transcription, and file-based / streaming speech recognition (ASR) across the StepAudio 2.5 and...
StepFun Realtime API
Bidirectional realtime voice over WebSocket (wss://api.stepfun.com/v1/realtime) with OpenAI Realtime-style session, conversation, and response events, plus a streaming TTS chann...
StepFun Images API
Image generation, image editing, and image-to-image endpoints for the step-2x-large and step-image-edit-2 models.
StepFun Files API
Upload, list, retrieve, delete files and fetch file content for use with Step models and knowledge bases.
StepFun Vector Stores API
Knowledge-base (vector store) management — create/list/retrieve/delete stores and attach or remove files for retrieval-augmented generation.
StepFun Web Search API
Web search and text-to-image search endpoints (POST /v1/search) billed per call as value-added capabilities.
StepFun Token Count API
Pre-count prompt tokens for a model request (POST /v1/token/count) to estimate usage and cost.
StepFun Accounts API
Retrieve account information including balances (GET /v1/accounts).
Scroll for all 12
MCP Servers 1
Model Context Protocol servers that expose these APIs to AI agents.
StepFun MCP Server
StepFun operates an official hosted remote MCP server, StepSearch — a search service built on the Model Context Protocol that gives Claude Code, Cline, OpenCode, Goose, and othe...
MCP SERVERStepFun API pricing
Prices published by StepFun, read 2026-10-07 from platform.stepfun.com/docs/zh/guides/pricing/details.
| Plan | Price |
|---|---|
| step-5-preview | 7 元 Includes: 输入价格(缓存未命中) |
| step-3.7-flash | 1.35 元 Includes: 输入价格(缓存未命中) |
| step-3.5-flash | 0.7 元 Includes: 输入(缓存未命中) |
| step-3.5-flash-2603 | 0.7 元 Includes: 输入(缓存未命中) |
| step-1o-turbo-vision | 2.5 元 Includes: 输入(缓存未命中) |
| stepaudio-2.5-realtime | 10 元 Includes: 输入(缓存未命中) |
| stepaudio-2.5-chat | 10 元 Includes: 输入(缓存未命中) |
| step-1o-audio | 25 元 Includes: 输入(缓存未命中) |
All 29 plans, limits and sources →
Rate limits
- V0 tier (cumulative top-up ¥0) — concurrency: 5 concurrent requests
- V0 tier — requests per minute: 10 requests per minute
- V0 tier — tokens per minute: 5000000 tokens per minute
Billed by: 1m tokens · FinOps profile →
Pricing Plans 1
Published pricing tiers and plan structures.
Rate Limits 1
Documented rate limits and quota policies.
Stepfun Rate Limits
RATE LIMITSFinOps 1
Cost, billing, and metering signals for API financial operations.
Stepfun Finops
FINOPSEvent Specifications 1
AsyncAPI definitions for this provider's event-driven and streaming APIs.
StepFun Realtime Voice & Streaming TTS WebSocket API
StepFun's realtime event surface: a bidirectional realtime voice channel at wss://api.stepfun.com/v1/realtime (OpenAI Realtime-style session / conversation / response events, mo...
ASYNCAPISecurity Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Resources
Get Started 3
Portal, sign-up, and the first successful call
Documentation 3
Reference material describing how the API behaves
Agent Surfaces 3
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 4
Pagination, idempotency, versioning, errors, and events
Build 3
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 3
Status, limits, changes, and where to get help
Commercial 4
Pricing, plans, and the legal terms of use
Company 2
The organization behind the API
Source (apis.yml)
StepFun API — frequently asked questions
Does StepFun have an API?
Yes. APIs.io lists 12 APIs from StepFun, including StepFun Chat Completions API, StepFun Messages API and StepFun Responses API, and 9 more.
How do I authenticate with the StepFun API?
StepFun uses bearer-token authentication (http-bearer-api-key · 1 scheme). The details are profiled on APIs.io as Stepfun Authentication.
How much does the StepFun API cost?
StepFun publishes its prices; its step-5-preview plan is 7 元 as of 2026-10-07. APIs.io lists 29 pricing plans for StepFun, with each plan's price, limits and inclusions under Pricing on this page.
Does StepFun have an MCP server?
Yes. APIs.io lists 1 MCP server for StepFun: StepFun operates an official hosted remote MCP server, StepSearch — a search service built on the Model Context Protocol that gives Claude Code, Cline, OpenCode, Goose, and other MCP-compatible client
Is the StepFun API ready for AI agents?
StepFun has a Kin Score of 56.0 out of 100 (strong) and an Agent Readiness score of 30.6 (agent-ready), scored by API Evangelist on 2026-11-06.
Work with this as data
Every provider here is available over the APIs.io API and to AI agents over MCP.