# Antseed vs StepFun API

> Antseed scores 55.1 (C) 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/antseed-vs-stepfun-api
- Markdown: https://www.anchorterminal.com/compare/antseed-vs-stepfun-api.md (~2,750 tokens)
- Slim: https://www.anchorterminal.com/compare/antseed-vs-stepfun-api.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/antseed-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

Antseed scores 55.1 (C) on agent readiness against StepFun API's 44.4 (E), and leads in 6 of 7 scored categories. StepFun API leads on agent ergonomics. Both do llm inference.

- Antseed: grade C, 55.1/100, rank #675 of 965. Markdown https://www.anchorterminal.com/tools/antseed.md · JSON https://www.anchorterminal.com/api/v1/tools/antseed.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

### Antseed (C)

Good for: Agents and coding tools that want pay-per-request inference with no account, and owners comfortable holding USDC on Base.

Ahead on:
- Reliability, 62 against 28
- Payments & pricing, 70 against 20
- Maintenance & community, 79 against 50

Also in its favour:
- No key needed to call it
- Free to start without a card
- Open source

Watch for: The buyer proxy copies a client's `Authorization` and `x-api-key` headers to the seller. The repository's March 2026 review flagged it and issue #1104 is open

### 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.

Ahead on:
- Agent ergonomics, 68 against 56

Also in its favour:
- A hosted endpoint, with nothing to install
- No incidents deducted, where Antseed loses 4 points for them

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


## Score by category

| Category | Weight | Antseed | StepFun API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 62 | 28 | Antseed +34 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 55 | 53 | Antseed +2 |
| Agent ergonomics | 13% (16.2 this run) | 56 | 68 | StepFun API +12 |
| Security & auth | 14% (17.5 this run) | 45 | 41 | Antseed +4 |
| Payments & pricing | 10% (12.5 this run) | 70 | 20 | Antseed +50 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 79 | 50 | Antseed +29 |
| Transparency & trust | 7% (8.8 this run) | 59 | 58 | Antseed +1 |
| Negative events | ≤15 | -4 | 0 | |
| **Total** | | **55.1 · C** | **44.4 · E** | |

## Facts side by side

| Fact | Antseed | StepFun API |
| --- | --- | --- |
| Kind | Model router | Model API |
| Vendor | Antseed Foundation | StepFun |
| Hosted endpoint | no (local only) | `https://api.stepfun.ai/v1` |
| Transports | HTTP | HTTP |
| Auth | None | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | GPL-3.0 (LICENSE in the repository). The @antseed/cli manifest on npm carries no licence field | 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 | 2026-10-08 | none |
| Terms last updated | 2026-05-15 |  |
| Privacy policy last updated | no document linked |  |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | 106 stars, 1.8k npm/wk | none |

## Verdicts

**Antseed.** A buyer needs no account. The CLI creates a wallet key, free models answer at once and paid ones draw on deposited USDC, with seller, tokens and cost returned in response headers. Sellers are unvetted and can read prompts unless TEE-verified, the proxy forwards a client's own credential headers to them, and every package is pre-1.0.

**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

### Antseed

1. Send a placeholder key such as `antseed-p2p`. The proxy forwards whatever `Authorization` or `x-api-key` header the client sends to the seller
2. Call `GET /v1/models` first and request a concrete id. The `antseed` alias works only when the desktop app has a model selected
3. Handle 402 `insufficient_deposits` by reading `suggestedAmount`, then fund the address from `antseed buyer deposit` with USDC on Base
4. Pass `--verifiers antseed-verifier --require-verifier` to `antseed buyer start` when prompts are private, so only TEE-verified sellers are routed
5. Read `x-antseed-peer-id` and `x-antseed-estimated-cost-usd` on each response, and pin a seller with `<peerId>@<model>` when the same one must answer

### 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, Antseed or StepFun API?

Antseed scores 55.1 (C) on agent readiness against StepFun API's 44.4 (E), and leads in 6 of 7 scored categories. StepFun API leads on agent ergonomics.

### Do Antseed and StepFun API need an API key?

Antseed needs no key. StepFun API needs an API key.

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

No hosted endpoint is listed for Antseed. StepFun API has a hosted endpoint at https://api.stepfun.ai/v1.

### Are Antseed and StepFun API open source?

Antseed is open source (GPL-3.0 (LICENSE in the repository). The @antseed/cli manifest on npm carries no licence field). No open-source release is listed for StepFun API.


## For agents

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

## Other comparisons with Antseed or StepFun API

- [Claude API vs Antseed](https://www.anchorterminal.com/compare/anthropic-api-vs-antseed.md)
- [Claude API vs StepFun API](https://www.anchorterminal.com/compare/anthropic-api-vs-stepfun-api.md)
- [Antseed vs BlockRun.AI](https://www.anchorterminal.com/compare/antseed-vs-blockrun-ai.md)
- [Antseed vs Cloudflare Workers AI](https://www.anchorterminal.com/compare/antseed-vs-cloudflare-workers-ai.md)
- [Antseed vs Cohere Chat API (Command models)](https://www.anchorterminal.com/compare/antseed-vs-cohere-chat.md)
- [Antseed vs DeepInfra](https://www.anchorterminal.com/compare/antseed-vs-deepinfra.md)
- [Antseed vs DeepSeek API](https://www.anchorterminal.com/compare/antseed-vs-deepseek-api.md)
- [Antseed vs Gemini Developer API](https://www.anchorterminal.com/compare/antseed-vs-gemini-api.md)
- [Antseed vs GroqCloud](https://www.anchorterminal.com/compare/antseed-vs-groq.md)
- [Antseed vs Mistral AI API](https://www.anchorterminal.com/compare/antseed-vs-mistral-api.md)
- [Antseed vs Novita AI](https://www.anchorterminal.com/compare/antseed-vs-novita-ai.md)
- [Antseed vs OpenAI API](https://www.anchorterminal.com/compare/antseed-vs-openai-api.md)
- [Antseed vs Prism Inference](https://www.anchorterminal.com/compare/antseed-vs-prism-inference.md)
- [Antseed vs SambaCloud](https://www.anchorterminal.com/compare/antseed-vs-sambanova.md)
- [Antseed vs SiliconFlow](https://www.anchorterminal.com/compare/antseed-vs-siliconflow.md)
- [BlockRun.AI vs StepFun API](https://www.anchorterminal.com/compare/blockrun-ai-vs-stepfun-api.md)
- [Cloudflare AI Gateway vs StepFun API](https://www.anchorterminal.com/compare/cloudflare-ai-gateway-vs-stepfun-api.md)
- [Cloudflare Workers AI vs StepFun API](https://www.anchorterminal.com/compare/cloudflare-workers-ai-vs-stepfun-api.md)
- [Cohere Chat API (Command models) vs StepFun API](https://www.anchorterminal.com/compare/cohere-chat-vs-stepfun-api.md)
- [DeepInfra vs StepFun API](https://www.anchorterminal.com/compare/deepinfra-vs-stepfun-api.md)
- [DeepSeek API vs StepFun API](https://www.anchorterminal.com/compare/deepseek-api-vs-stepfun-api.md)
- [Gemini Developer API vs StepFun API](https://www.anchorterminal.com/compare/gemini-api-vs-stepfun-api.md)
- [GroqCloud vs StepFun API](https://www.anchorterminal.com/compare/groq-vs-stepfun-api.md)
- [Mistral AI API vs StepFun API](https://www.anchorterminal.com/compare/mistral-api-vs-stepfun-api.md)
- [Novita AI vs StepFun API](https://www.anchorterminal.com/compare/novita-ai-vs-stepfun-api.md)
- [OpenAI API vs StepFun API](https://www.anchorterminal.com/compare/openai-api-vs-stepfun-api.md)
- [OpenRouter vs StepFun API](https://www.anchorterminal.com/compare/openrouter-vs-stepfun-api.md)
- [Prism Inference vs StepFun API](https://www.anchorterminal.com/compare/prism-inference-vs-stepfun-api.md)
- [SambaCloud vs StepFun API](https://www.anchorterminal.com/compare/sambanova-vs-stepfun-api.md)
- [SiliconFlow vs StepFun API](https://www.anchorterminal.com/compare/siliconflow-vs-stepfun-api.md)
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