Benchmark Almanac

NaturalCodeBench

Seed-Coder-8B-Instruct 49.6% leads since Jun 2025 Dropped

Models solve 402 Python and Java problems taken from real user queries to online coding services in 6 domains. Semi-automatically built tests check each solution.

Prompts come in Chinese and English versions. Labs report a total over both.

In the authors’ words

Large language models (LLMs) have manifested strong ability to generate codes for productive activities. However, current benchmarks for code synthesis, such as HumanEval, MBPP, and DS-1000, are predominantly oriented towards introductory tasks on algorithm and data science, insufficiently satisfying challenging requirements prevalent in real-world coding. To fill this gap, we propose NaturalCodeBench (NCB), a challenging code benchmark designed to mirror the complexity and variety of scenarios in real coding tasks. NCB comprises 402 high-quality problems in Python and Java, meticulously selected from natural user queries from online coding services, covering 6 different domains. Noting the extraordinary difficulty in creating testing cases for real-world queries, we also introduce a semi-automated pipeline to enhance the efficiency of test case construction. Comparing with manual solutions, it achieves an efficiency increase of more than 4 times. Our systematic experiments on 39 LLMs find that performance gaps on NCB between models with close HumanEval scores could still be significant, indicating a lack of focus on practical code synthesis scenarios or over-specified optimization on HumanEval. On the other hand, even the best-performing GPT-4 is still far from satisfying on NCB. The evaluation toolkit and development set are available at https://github.com/THUDM/NaturalCodeBench.

Abstract of NaturalCodeBench: Examining Coding Performance Mismatch on HumanEval and Natural User Prompts (arXiv:2405.04520, CC0)
Made by Tsinghua University and Zhipu AI (THUDM) Released May 2024 Function-level problems Last in a launch post Jul 2025 , dropped before it saturated Last model added Aug 2025
Level
University Undergraduates and entry-level professionals
Scored
Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
Answers
Code A program or patch run against tests.
2
Models scored in lab cards
1
Launch post lists it, from 1 lab
2
System cards report it, from 1 lab

Seed-Coder-8B-Instruct leads with 49.6%

Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.

  1. 1 Seed-Coder-8B-Instruct 49.6%
  2. 2 Seed Diffusion Preview 42.2%
#ModelScoreSettingDateSource
1 Seed-Coder-8B-Instruct 49.6% Jun 2025 Model card
2 Seed Diffusion Preview 42.2% Jul 2025 Model card

Number one over time

Lab claims count from the day the card came out, independent runs from the model’s release.

ByteDance Seed
Lab claims Not tested since Aug 2025

Scores over time

All the scores we have, one dot each, so a model tested at several settings appears more than once.

Reported by the lab in its model card
0% 20% 40% 60% 80% 100% 2025 Near the ceiling (85%) Seed-Coder-8B-Instruct 0% 20% 40% 60% 80% 100% 2025 Near the ceiling (85%) Seed-Coder-8B-Instruct

No launch post has listed it since Jul 2025

Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.

ByteDance Seed
DateLaunch postScoreAs the post writes it
31 Jul 2025 Seed Diffusion Preview 42.2 NaturalCodeBench Total

2 system cards report it, from 1 lab

Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.

DateDocumentScoreAs the document writes itSection
4 Aug 2025 Seed Diffusion Preview technical report 42.2 NaturalCodeBench Total, NCB (zh) 45.8, NCB (en) 38.6 (Table 3) Capabilities
4 Jun 2025 Seed-Coder-8B-Instruct technical report 49.6 NaturalCodeBench Total (Table 9). NCB (zh) 50.7, NCB (en) 48.6 Capabilities

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