---
title: "Step 3.5 Flash API pricing"
canonical: https://uplinkswitch.ai/models/step-3.5-flash
generated: 2026-10-25T13:45:00.253Z
source: https://api.uplinkswitch.com/v1/catalog
base_url: https://api.uplinkswitch.com/v1
---

# Step 3.5 Flash API pricing

Step 3.5 Flash API at $0.40/M input and $1.20/M output tokens. Works with the OpenAI SDK.

## Price per million tokens (USD)

| Tokens | StepFun list price | UplinkSwitch | Under list |
| --- | --- | --- | --- |
| Input | — | $0.40 | — |
| Cached input | — | billed at the input rate | — |
| Output | — | $1.20 | — |

## Model

- Model id: `step-3.5-flash`
- Formats: OpenAI SDK
- Base URL: https://api.uplinkswitch.com/v1
- Daily real-model check: Steady since Oct 20 (https://uplinkswitch.ai/proof#step-3.5-flash)

## Step 3.5 Flash API key

1. Create a key in the console at uplinkswitch.ai/console. Credit is prepaid from $10 with no subscription, and the key works at once.
2. Point your SDK or tool at https://api.uplinkswitch.com/v1, for example with OPENAI_BASE_URL, and send the key as the bearer token.
3. Send step-3.5-flash as the model. The same key calls every other model in the catalog.

## Request

### Python · OpenAI SDK

```python
from openai import OpenAI

client = OpenAI(
    base_url="https://api.uplinkswitch.com/v1",
    api_key="sk-uplink-live-...",
)

completion = client.chat.completions.create(
    model="step-3.5-flash",
    messages=[{"role": "user", "content": "Summarize this in one line."}],
)
print(completion.choices[0].message.content)
```

### TypeScript · OpenAI SDK

```typescript
import OpenAI from 'openai';

const client = new OpenAI({
  baseURL: 'https://api.uplinkswitch.com/v1',
  apiKey: 'sk-uplink-live-...',
});

const completion = await client.chat.completions.create({
  model: 'step-3.5-flash',
  messages: [{ role: 'user', content: 'Summarize this in one line.' }],
});
console.log(completion.choices[0].message.content);
```

### curl

```bash
curl https://api.uplinkswitch.com/v1/chat/completions \
  -H "authorization: Bearer sk-uplink-live-..." \
  -H "content-type: application/json" \
  -d '{"model":"step-3.5-flash","messages":[{"role":"user","content":"Hello"}]}'
```

## Questions

### What is Step 3.5 Flash?

Step 3.5 Flash is a model from StepFun. Through UplinkSwitch it answers the OpenAI SDK on one key as step-3.5-flash.

### How much does the Step 3.5 Flash API cost?

$0.40 per million input tokens and $1.20 per million output tokens.

### Is Step 3.5 Flash free?

It is pay as you go: prepaid credit from $10, with no subscription or monthly fee, billed per token. A 1,000-token prompt with a 500-token reply costs about $0.001.

### What is the Step 3.5 Flash model id?

step-3.5-flash. Send it as the model through the OpenAI SDK with base URL https://api.uplinkswitch.com/v1.

### How do I get a Step 3.5 Flash API key?

Create one in the console at uplinkswitch.ai/console: prepaid credit from $10, no subscription, and the key is live at once. The same key calls Step 3.5 Flash and every other model in the catalog; send it as the bearer token with base URL https://api.uplinkswitch.com/v1.

### Is it the real Step 3.5 Flash?

Every day each model gets the same test prompt, and the results are public on /proof. Step 3.5 Flash's latest result: Steady since Oct 20.

### Is there a Step 3.5 Flash API?

Yes: step-3.5-flash on the OpenAI format at https://api.uplinkswitch.com/v1, $0.40 input and $1.20 output per million tokens. No weights to download and no GPU of your own; the key also runs every other model in the catalog.

### How many parameters does Step 3.5 Flash have?

196B total, 11B active per token, per stepfun-ai/Step-3.5-Flash.

### What is Step 3.5 Flash's context window?

256K tokens, per stepfun-ai/Step-3.5-Flash.

### Is Step 3.5 Flash open source?

Its weights are open on Hugging Face (stepfun-ai/Step-3.5-Flash); the license is Apache-2.0.

### What does Step 3.5 Flash cost per 100 messages?

$0.14 for 100 chat turns of 2,000 input and 500 output tokens each, at $0.40 input and $1.20 output per million tokens, from prepaid credit with no subscription.

## Related

- Cursor setup: https://uplinkswitch.ai/guides/cursor
- Cline setup: https://uplinkswitch.ai/guides/cline
- Roo Code setup: https://uplinkswitch.ai/guides/roo-code
- Kilo Code setup: https://uplinkswitch.ai/guides/kilo-code
- SDKs setup: https://uplinkswitch.ai/guides/sdks
- Every model and price: https://uplinkswitch.ai/llms-full.txt
- Machine catalog: https://uplinkswitch.ai/ai-catalog.json