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Inception · Efficient

Mercury Coder Small

Added Jan 1, 2024

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Use in the app

Model by Inception AI. A diffusion large language model that runs incredibly quickly (500+ tokens/second) while matching Claude 3.5 Haiku and GPT-4o-mini. 1st in speed on Copilot arena, and matching 2nd in quality.

Input
Text
Output
Text
Discovery tier
Efficient

Pricing

USD per 1M tokens
Input
$0.25
Output
$1.00

Reference prices as published by the model provider. API example

Specifications

Context window
32.8K
Max output
16.4K

Side by side

Mercury Coder Small compared

Specifications, prices, speed and benchmark scores next to each other. Benchmarks below show every compared model too.

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Mercury Coder SmallInceptionThis modelGPT 5.1 Codex MiniOpenAIRemove
ProviderInceptionOpenAI
Discovery tierEfficientEfficient
AddedJan 1, 2024Nov 13, 2025
Limits
Context window32.77K400KBest
Max output16.38K128KBest
Average output—136 tokens
Pricing, USD per 1M tokens
Input$0.25$0.25
Output$1.00Best$2.00
Cache read—$0.025
Benchmark indexes
Intelligence Index—20.4
Math Index—91.7
Capabilities
ReasoningNoYes
VisionNoYes
Reasoning effort——

Public evaluations

Benchmarks

Independent evaluation results, with how each score ranks among the models in the Noumen catalog.

  • Mercury Coder Small
  • GPT 5.1 Codex Mini

Intelligence Index

  • Mercury Coder Small—
  • GPT 5.1 Codex Mini20.4
3.8Catalog models by score55.1

Indexes

  • Math Index

    Composite of the math evaluations

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 91.7

Document reasoning

  • AA-LCRv1.1

    Reasoning across long documents

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 66.7%

Reasoning and knowledge

  • Humanity’s Last Exam

    Expert-level questions across academic fields

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 18.5%

  • GPQA Diamond

    Graduate-level science questions

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 81.3%

  • MMLU-Pro

    Multi-subject knowledge and reasoning

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 82.0%

  • IFBench

    Following precise output instructions

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 67.9%

Coding

  • LiveCodeBench

    Recent competitive programming problems

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 83.6%

Math

  • AIME 2025

    Competition mathematics, 2025 problems

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 91.7%

Legacy evaluations

  • Terminal-Bench Hard

    Earlier terminal task suite

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 33.3%

  • τ²-Bench Telecom

    Tool use in a customer-support simulation

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 62.9%

  • AA-LCR (unversioned)

    Long-context reasoning, earlier grading

    • Mercury Coder Small: —
    • GPT 5.1 Codex Mini: 66.7%

Scores from Artificial Analysis, updated Oct 26, 2026. Artificial Analysis

Developers

Use it through the API

Noumen’s API is OpenAI-compatible: any Chat Completions client works with a base URL and a key.

Read the quickstart
curl https://www.noumen.xyz/api/v1/chat/completions \
  -H "Authorization: Bearer $NOUMEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "mercury-coder-small",
    "messages": [{ "role": "user", "content": "Explain this stack trace." }]
  }'
import os
from openai import OpenAI

client = OpenAI(base_url="https://www.noumen.xyz/api/v1", api_key=os.environ["NOUMEN_API_KEY"])
reply = client.chat.completions.create(
    model="mercury-coder-small",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

Inception

Other Inception models, starting with the same family.