> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bettertoken.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# DeepSeek V4.1 Flash limited test is live

> Test DeepSeek V4.1 Flash on BetterToken with the temporary Model ID deepseek-v4.1-flash-expires-on-0910 before its scheduled 2026-09-10 expiration.

Updated: September 9, 2026

BetterToken now provides limited test access to **DeepSeek V4.1 Flash** through the exact Model ID `deepseek-v4.1-flash-expires-on-0910`. This temporary entry is scheduled to expire on **September 10, 2026**. Use it to evaluate the model, not as a permanent production configuration. Check current access and pricing in the <a href={"https://bettertoken.ai/pricing"}>model plaza</a> before sending a request.

<Warning>
  The temporary Model ID includes its expiration date. It may stop working after September 10, 2026, and it is not automatically replaced by a future stable ID. Keep a stable fallback model ready.
</Warning>

## What is available now

| Setting                 | Value                                                   |
| ----------------------- | ------------------------------------------------------- |
| Provider                | **DeepSeek**                                            |
| Model ID                | `deepseek-v4.1-flash-expires-on-0910`                   |
| OpenAI Base URL         | `https://bettertoken.ai/v1`                             |
| OpenAI Chat Completions | `POST /v1/chat/completions`                             |
| Anthropic Base URL      | `https://bettertoken.ai`                                |
| Anthropic Messages      | `POST /v1/messages`                                     |
| BetterToken status      | Limited test; scheduled to expire on September 10, 2026 |

Choose OpenAI Chat Completions or Anthropic Messages to match your client. Both protocols use the same BetterToken API Key and Model ID.

## Usage suggestions

Use the test window to compare DeepSeek V4.1 Flash with the stable DeepSeek V4 Flash entry on tasks that matter to your workflow:

* **Coding changes**: give both models the same repository task and compare correctness, edit quality, and the amount of follow-up required
* **Agent workflows**: measure how reliably each model follows multistep instructions and uses the tools your client provides
* **Reasoning quality**: compare difficult debugging, planning, and analysis tasks with the same prompt and evaluation criteria
* **Latency and cost**: record time to first token, total completion time, token usage, and the live BetterToken price

Run several representative prompts instead of relying on one result. Keep the client, system prompt, tool definitions, and sampling settings the same for a fair comparison.

## Quick start

1. <a href={"https://bettertoken.ai/register"}>Create a BetterToken API Key</a> or open **Setup** for an existing key.
2. Confirm that `deepseek-v4.1-flash-expires-on-0910` is still available in the model plaza.
3. Select the **DeepSeek provider**.
4. Set the Base URL for your protocol using the table above, and enter the complete Model ID.
5. Send a small request before running a longer evaluation.

```bash theme={null}
curl "https://bettertoken.ai/v1/chat/completions" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  --data '{
    "model": "deepseek-v4.1-flash-expires-on-0910",
    "messages": [
      {
        "role": "user",
        "content": "Explain the likely cause of this failing test and propose the smallest fix."
      }
    ]
  }'
```

A successful response returns model output under `choices[0].message.content`. For SDK examples and the complete request format, see the [Chat Completions API reference](/en/api-reference/chat-completions).

## Prepare for expiration

Before September 10, 2026:

1. Find every configuration that contains `deepseek-v4.1-flash-expires-on-0910`.
2. Save the evaluation results you need.
3. Replace the temporary ID with `deepseek-v4-flash-0731` or another currently available Model ID.
4. Run a smoke test after the change.
5. Check the model plaza for any new stable V4.1 entry. Do not guess its Model ID.

## Frequently asked questions

### Can I use this Model ID in production?

You can send requests while the entry is available, but you should not make it the only model in a long-lived production configuration. Its scheduled expiration can cause requests to fail after the test ends.

### Can I use it with Claude Code or the Anthropic Messages API?

Yes. For Claude Code or Anthropic Messages, use Base URL `https://bettertoken.ai` and Model ID `deepseek-v4.1-flash-expires-on-0910`. Direct Messages requests use `POST /v1/messages` with your BetterToken API Key in `x-api-key`.

### Where can I find the current price?

Check the live <a href={"https://bettertoken.ai/pricing"}>model plaza</a>. Temporary-model availability and pricing can change during the test.

## Related documentation

* [BetterToken Chat Completions API reference](/en/api-reference/chat-completions)
* [Anthropic Messages API reference](/en/api-reference/messages)