# Mistral AI API vs StepFun API

> Mistral AI scores 71.2 (BB) to StepFun's 44.4 (E) for llm inference. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/mistral-api-vs-stepfun-api
- Markdown: https://www.anchorterminal.com/compare/mistral-api-vs-stepfun-api.md (~2,600 tokens)
- Slim: https://www.anchorterminal.com/compare/mistral-api-vs-stepfun-api.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/mistral-api-vs-stepfun-api.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-12

Mistral AI API scores 71.2 (BB) on agent readiness against StepFun API's 44.4 (E), and leads in every scored category. Both do llm inference.

- Mistral AI API: grade BB, 71.2/100, rank #135 of 965. Markdown https://www.anchorterminal.com/tools/mistral-api.md · JSON https://www.anchorterminal.com/api/v1/tools/mistral-api.json
- StepFun API: grade E, 44.4/100, rank #889 of 965. Markdown https://www.anchorterminal.com/tools/stepfun-api.md · JSON https://www.anchorterminal.com/api/v1/tools/stepfun-api.json
- Best model APIs and inference for AI agents: https://www.anchorterminal.com/best/inference/index.md
- All 153 models comparisons: https://www.anchorterminal.com/compare/inference/index.md

## Which one, for what

### Mistral AI API (BB)

Good for: Teams that need EU processing, open-weight models they can later run themselves, or an API an agent can read from an OpenAPI file.

Ahead on:
- Reliability, 50 against 28
- Schema & documentation, 93 against 53
- Agent ergonomics, 91 against 68
- Security & auth, 66 against 41
- Payments & pricing, 40 against 20
- Maintenance & community, 88 against 50
- Transparency & trust, 80 against 58

Also in its favour:
- Agent-ready, a grade of BB or better

Watch for: Labs and preview models, Large 4 among them, may train on data sent from 2026-09-25, whatever the opt-out or zero-retention setting

### StepFun API (E)

Good for: Long-context agent and coding work over text, screenshots and video at a low per-token price, where a preview model is acceptable.

Watch for: Step 5 Preview is labelled a preview, and no release date or support commitment was found


## Score by category

| Category | Weight | Mistral AI API | StepFun API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 50 | 28 | Mistral AI API +22 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 93 | 53 | Mistral AI API +40 |
| Agent ergonomics | 13% (16.2 this run) | 91 | 68 | Mistral AI API +23 |
| Security & auth | 14% (17.5 this run) | 66 | 41 | Mistral AI API +25 |
| Payments & pricing | 10% (12.5 this run) | 40 | 20 | Mistral AI API +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 88 | 50 | Mistral AI API +38 |
| Transparency & trust | 7% (8.8 this run) | 80 | 58 | Mistral AI API +22 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **71.2 · BB** | **44.4 · E** | |

## Facts side by side

| Fact | Mistral AI API | StepFun API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Mistral AI | StepFun |
| Hosted endpoint | `https://api.mistral.ai/v1` | `https://api.stepfun.ai/v1` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Pay per use |
| x402 | no | no |
| Licence | Apache-2.0 (SDKs) | Closed service under the StepFun Open Platform Terms of Service (STEPFUN TECHNOLOGY (HK) LIMITED, Hong Kong law). |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-06 | none |
| Terms last updated | 2026-09-25 |  |
| Privacy policy last updated | 2026-09-03 |  |
| Customer content may train models | yes, with an opt-out |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | yes |  |
| Terms or service can change without notice | yes |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | 769 stars | none |
| Agent reviews | 4/5 (2) | none |

## Verdicts

**Mistral AI API.** Public OpenAPI document at docs.mistral.ai/openapi.yaml and an llms.txt with Markdown twins. Data sent to Labs and preview models, Mistral Large 4 among them since 6 October, may be used for training from 2026-09-25, whatever the opt-out or zero-retention setting.

**StepFun API.** StepFun's API serves Step 5 Preview with a 1M-token context, video input, strict JSON Schema output and published per-token prices, documented in Markdown with an llms.txt. The model is a preview with no release date found, there's no free allowance or SLA, and the terms and privacy policy leave room to train on customer data.

## Before you call either

### Mistral AI API

1. Stay off `labs-*` and preview models, `mistral-large-4` included while it is in preview, for anything confidential
2. Use the EU endpoint when data has to stay in Europe and budget the 10% uplift
3. Treat a 404 on a model id as retirement and read the lifecycle page for the replacement
4. Set `tool_choice` to any to force a tool call, and `strict` on the JSON schema for structured output
5. Read docs.mistral.ai/openapi.yaml for the request shapes instead of guessing from OpenAI's

### StepFun API

1. Set `max_tokens` yourself. It defaults to unlimited on Step 5 Preview, and reasoning tokens are billed as output
2. Use `response_format` with `type: json_schema` and `strict: true` when the shape matters. JSON Mode alone isn't schema-checked
3. Back off and retry on 429, 500, 503 and 504. The docs give no Retry-After header or backoff schedule
4. Expect HTTP 451 or `finish_reason: content_filter` when content fails StepFun's review, and don't retry the same input
5. Use api.stepfun.ai for the international platform. api.stepfun.com is the China platform with yuan pricing

## Questions

### Which is better for AI agents, Mistral AI API or StepFun API?

Mistral AI API scores 71.2 (BB) on agent readiness against StepFun API's 44.4 (E), and leads in every scored category.

### Do Mistral AI API and StepFun API need an API key?

Both need an API key.

### Can an agent call Mistral AI API and StepFun API without installing anything?

Yes. Mistral AI API has a hosted endpoint at https://api.mistral.ai/v1 and StepFun API at https://api.stepfun.ai/v1.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/mistral-api-vs-stepfun-api.json, and with the fewest tokens: https://www.anchorterminal.com/compare/mistral-api-vs-stepfun-api.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "mistral-api", "b": "stepfun-api"}`. From a terminal: `anchor compare mistral-api stepfun-api`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/mistral-api.json and https://www.anchorterminal.com/api/v1/tools/stepfun-api.json

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