How much does the Mercury 2.5 API cost?

On FastMetal, Mercury 2.5 is billed per token in yen: ¥6.77 per 1M input tokens and ¥25.38 per 1M output tokens, before tax. Usage is drawn from a prepaid balance; there is no subscription or monthly fee.

Can I call Mercury 2.5 with the OpenAI SDK?

Yes. Point base_url at https://api.fastmetal.ai/v1 and pass "mercury-2.5" as the model; existing OpenAI-style code works unchanged, including streaming, tool calls and structured output.

What is the context window of Mercury 2.5?

260,000 tokens, shared between the prompt and the response.

What do I need to try Mercury 2.5?

Create an account and add credit; the model is then available both in the browser chat and over the API. There is no contract or minimum spend.

Back to Models

inception/mercury-2-5

Mercury 2.5

Mercury 2.5 is the fastest reasoning LLM, and the latest diffusion LLM (dLLM) from Inception. Instead of generating tokens sequentially, Mercury 2.5 produces and refines multiple tokens in parallel, achieving...

9/8/2026

260,000 tokens

Input: ¥6.768/M

Output: ¥25.3799/M

Try in Chat Get API Key

Specifications

Modalities

Input

text

Output

text

Supported Parameters

include_reasoning

max_tokens

reasoning

reasoning_effort

response_format

stop

structured_outputs

temperature

tool_choice

tools

Max Output Tokens

65,536

Reasoning Configuration

Default: Thinking on (effort: medium)
Selectable effort levels: high
medium
low
none
Turning thinking off: Possible (reasoning.enabled: false)

How to control thinking, and what it costs

Code Examples

curl https://api.fastmetal.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "mercury-2.5",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

How Mercury 2.5 actually answers

Real responses to our standard prompts, recorded on FastMetal.

Count the number of 'r's in 'strawberry'

Count the number of 'r's in 'strawberry'. Explain your reasoning step by step.

To determine the number of 'r's in the word "strawberry", we can examine each letter in sequence: 1. **s** - Not 'r' 2. **t** - Not 'r' 3. **r** - First 'r' found 4. **a** - Not 'r' 5. **w** - Not 'r' 6. **b** - Not 'r' 7. **e** - Not 'r' 8. **r** - Second 'r' found 9. **r** - Third 'r' found 10. **y** - Not 'r' Counting these occurrences, there are **3** 'r's in "strawberry".

1.8s response968 output tokens

Debug This Error

I'm getting the following error in my Node.js application: TypeError: Cannot read properties of undefined (reading 'map') at UserList (/app/components/UserList.js:12:25) at renderWithHooks (/app/node_modules/rea…

This error occurs because the `users` prop is `undefined` when the component renders. Since the code calls `.map()` on `users`, JavaScript throws a TypeError when `users` is not an array. Here is how to fix it: 1. **Set a Default Value** Update the function signature to default `users` to an empty array if it is not provided: ```javascript function UserList({ users = [] }) { // ... } ``` 2. **Add a Conditional Check** If `users` might be null or undefined during data loading, guard the map operation: ```javascript {users && users.map(user => <li key={user.id}>{user.name}</li>)} ``` 3. **Verify Parent Props** Ensure the parent component pas…

2.4s response1028 output tokens

Code Review

Please review the following Python function and suggest improvements for readability, performance, and best practices: def get_data(url, retries=3): import requests import time for i in range(retries):…

Here is a review of the function with suggestions for improvement. ### Key Observations 1. **Imports:** Libraries should be imported at the module level, not inside functions. 2. **Exception Handling:** Bare `except:` clauses catch system exits and interrupts. Use specific exceptions like `requests.exceptions.RequestException`. 3. **Logic & Pythonicity:** * Avoid `== True`; rely on truthiness or `item.get("active")`. * List comprehensions are more concise and efficient than manual appending. 4. **Retry Strategy:** Implement exponential backoff instead of fixed sleeps, and avoid sleeping after the final failed attempt. 5. **Documentation:** Add type hints and a docstring fo…

4.6s response1999 output tokens

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Frequently asked questions

How much does the Mercury 2.5 API cost?: On FastMetal, Mercury 2.5 is billed per token in yen: ¥6.77 per 1M input tokens and ¥25.38 per 1M output tokens, before tax. Usage is drawn from a prepaid balance; there is no subscription or monthly fee.
Can I call Mercury 2.5 with the OpenAI SDK?: Yes. Point base_url at https://api.fastmetal.ai/v1 and pass "mercury-2.5" as the model; existing OpenAI-style code works unchanged, including streaming, tool calls and structured output.
What is the context window of Mercury 2.5?: 260,000 tokens, shared between the prompt and the response.
What do I need to try Mercury 2.5?: Create an account and add credit; the model is then available both in the browser chat and over the API. There is no contract or minimum spend.

Try Mercury 2.5 right now

Mercury 2.5 is available on FastMetal through one API key. Start in the browser, or call it from the OpenAI SDK.

Create a free account

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