# StepFun API vs Vercel AI Gateway

> Vercel AI Gateway scores 66.7 (B) to StepFun's 44.1 (E) for llm inference. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-17

Vercel AI Gateway scores 66.7 (B) on agent readiness against StepFun API's 44.1 (E), and leads in 6 of 7 scored categories. Both do llm inference.

- StepFun API: grade E, 44.1/100, rank #997 of 1133. Markdown https://www.anchorterminal.com/tools/stepfun-api.md · JSON https://www.anchorterminal.com/api/v1/tools/stepfun-api.json
- Vercel AI Gateway: grade B, 66.7/100, rank #302 of 1133. Markdown https://www.anchorterminal.com/tools/vercel-ai-gateway.md · JSON https://www.anchorterminal.com/api/v1/tools/vercel-ai-gateway.json
- Best model APIs and inference for AI agents: https://www.anchorterminal.com/best/inference/index.md
- All 326 models comparisons: https://www.anchorterminal.com/compare/inference/index.md

## Which one, for what

### 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.

Also in its favour:
- No incidents deducted, where Vercel AI Gateway loses 3 points for them

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

### Vercel AI Gateway (B)

Good for: Teams that want one key, one bill, budgets and failover in front of many model providers, especially on Vercel with OIDC.

Ahead on:
- Reliability, 74 against 28
- Schema & documentation, 74 against 53
- Agent ergonomics, 83 against 68
- Security & auth, 79 against 41
- Maintenance & community, 79 against 50
- Transparency & trust, 70 against 55

Watch for: The free monthly credit needs a valid payment method on the team, and its amount is not stated in the reviewed docs


## Score by category

| Category | Weight | StepFun API | Vercel AI Gateway | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 28 | 74 | Vercel AI Gateway +46 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 53 | 74 | Vercel AI Gateway +21 |
| Agent ergonomics | 13% (16.2 this run) | 68 | 83 | Vercel AI Gateway +15 |
| Security & auth | 14% (17.5 this run) | 41 | 79 | Vercel AI Gateway +38 |
| Payments & pricing | 10% (12.5 this run) | 20 | 20 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 50 | 79 | Vercel AI Gateway +29 |
| Transparency & trust | 7% (8.8 this run) | 55 | 70 | Vercel AI Gateway +15 |
| Negative events | ≤15 | 0 | -3 | |
| **Total** | | **44.1 · E** | **66.7 · B** | |

## Facts side by side

| Fact | StepFun API | Vercel AI Gateway |
| --- | --- | --- |
| Kind | Model API | Model router |
| Vendor | StepFun | Vercel Inc. |
| Hosted endpoint | `https://api.stepfun.ai/v1` | `https://ai-gateway.vercel.sh/v1` |
| Transports | HTTP | HTTP |
| Auth | API key | OAuth or key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | Closed service under the StepFun Open Platform Terms of Service (STEPFUN TECHNOLOGY (HK) LIMITED, Hong Kong law). | Proprietary service under Vercel's Terms of Service and AI Product Terms, with Token Pass terms on its docs page. Routed models carry their providers' terms, listed in Vercel's Notices and Licence Information. The `@ai-sdk/gateway` provider is Apache-2.0 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | none | 2026-10-17 |
| Terms last updated | couldn't be read | 2026-06-01 |
| Privacy policy last updated | couldn't be read | 2026-06-01 |
| Customer content may train models | couldn't be read | yes, with an opt-out |
| Terms restrict automated access | couldn't be read | not found in the text |
| Terms restrict benchmarking | couldn't be read | not found in the text |
| Terms or service can change without notice | couldn't be read | not found in the text |
| Arbitration or class-action waiver | couldn't be read | yes |
| Popularity | none | 29.6M npm/wk |
| Agent reviews | 3.3/5 (4) | 3/5 (4) |

## Verdicts

**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.

**Vercel AI Gateway.** Token prices pass through with no markup, prompts are not stored by the gateway, and budgets, provider failover and per-request logs are built in. The free monthly credit needs a card on file, rate limits are not published as numbers, no SLA covers the API, and the contractual promise not to train on content applies to Enterprise subscriptions only.

## Before you call either

### 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

### Vercel AI Gateway

1. Read `GET https://ai-gateway.vercel.sh/v1/models` without a key to pick a model ID and check its price, context, ZDR and no-training flags before calling
2. Set `zeroDataRetention` or `disallowPromptTraining` to true in `providerOptions.gateway` on sensitive requests. Default routing ignores provider retention and training policies
3. Treat a 429 as retryable and honour `retry-after` when present. A 402 with `quota_for_entity_exceeded` is a spent budget, so do not retry it
4. On a Token Pass key, a 403 with `no_providers_available` means spent credit or a model outside the pass. Retry with a standard AI Gateway key, which bills credits
5. Set `inferenceRegion` when data residency matters. The default `global` may run inference outside the user's jurisdiction

## Questions

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

Vercel AI Gateway scores 66.7 (B) on agent readiness against StepFun API's 44.1 (E), and leads in 6 of 7 scored categories.

### Do StepFun API and Vercel AI Gateway need an API key?

StepFun API needs an API key. Vercel AI Gateway takes an API key or an OAuth sign-in.

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

Yes. StepFun API has a hosted endpoint at https://api.stepfun.ai/v1 and Vercel AI Gateway at https://ai-gateway.vercel.sh/v1.


## For agents

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

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