Benchmark Almanac

AetherCode

o4-mini 35.5% leads since August 2025
Seed2.1 Pro 65.8% leads since June 2026
Fading

Models write solutions to problems from premier programming contests such as IOI and ICPC. Expert-validated test suites judge each solution.

Test cases mix automatic generation with human curation to remove weak tests.

Released
August 2025
Kind
Competitive programming
Level
Competition
Scored
Checked automatically
Answers
Code
Strongest model tested
o4-mini #94 on the capability index
Last in a launch post
February 2026, dropped before it saturated
Last model added
June 2026
Scores refreshed
November 12th, 2026

In the authors’ words

Competitive programming has emerged as a critical benchmark for evaluating the reasoning and coding capabilities of Large Language Models (LLMs). Despite impressive progress on existing benchmarks, we argue that current evaluations overstate model proficiency, masking a substantial gap between LLMs and elite human programmers. This gap arises from two key limitations: insufficient difficulty and scope of benchmark problems, and evaluation bias from low-quality test cases. To address these shortcomings, we present AetherCode, a new benchmark that draws problems from premier programming competitions such as IOI and ICPC, offering broader coverage and higher difficulty. AetherCode further incorporates comprehensive, expert-validated test suites built through a hybrid of automated generation and human curation, ensuring rigorous and reliable assessment. By combining challenging problem design with robust evaluation, AetherCode provides a more faithful measure of LLM capabilities and sets a new standard for future research in code reasoning.

Abstract of AetherCode: Evaluating LLMs' Ability to Win In Premier Programming Competitions (arXiv:2508.16402, CC0)
13
Entries on its own leaderboard, 9 models we track
2
Launch posts list it, from 1 lab
3
System cards report it, from 1 lab

o4-mini leads with 35.5% among models released by September 2025

Best score per entry from the benchmark's own leaderboard, read on November 12th, 2026. Where a model ran with several settings or harnesses, we keep its best. Names in gray aren't in our model list: fine-tunes, agent systems, products and older models. They don't count toward leaders.

Seed2.1 Pro leads with 65.8%, claims included

Best score per model from every source, including labs’ own numbers and claims Epoch AI collected from reports and papers. Labs pick their own settings, so a claim can beat an independent run of the same model.

The newest model with a score here came out in September 2025, and nobody has tested a newer one. Among the 20 highest-ranked models on the capability index, these have no score yet:

  1. 1 o4-mini high 35.5%
  2. 2 Gemini-2.5-Pro [snapshot unspecified] 32.7%
  3. 3 Seed-1.6-thinking-0715 26.6%
  4. 4 DeepSeek-R1 May 2025 22.3%
  5. 5 Gemini-2.5-Flash [snapshot unspecified] 20.3%
  6. 6 Qwen3-235B-A22B 17.6%
  7. 7 Qwen3-32B 16.3%
  8. 8 GPT-4.1 10.5%
  9. 9 Qwen3-8B 10%
  10. 10 Kimi K2 Sep 2025 9.80%
  11. 11 DeepSeek-V3 Mar 2025 8.50%
  12. 12 Qwen3-Coder-480B-A35B 7.70%
  13. 13 GPT-4o [snapshot unspecified] 4.40%

Source: Official AetherCode leaderboard

#EntryScoreSettingDateSource
1 o4-mini 35.5% high Apr 2025 Official leaderboard
2 Gemini-2.5-Pro [snapshot unspecified] 32.7% Official leaderboard
3 Seed-1.6-thinking-0715 26.6% Official leaderboard
4 DeepSeek-R1 May 2025 22.3% May 2025 Official leaderboard
5 Gemini-2.5-Flash [snapshot unspecified] 20.3% Official leaderboard
6 Qwen3-235B-A22B 17.6% Apr 2025 Official leaderboard
7 Qwen3-32B 16.3% Apr 2025 Official leaderboard
8 GPT-4.1 10.5% Apr 2025 Official leaderboard
9 Qwen3-8B 10% Apr 2025 Official leaderboard
10 Kimi K2 Sep 2025 9.80% Sep 2025 Official leaderboard
11 DeepSeek-V3 Mar 2025 8.50% Mar 2025 Official leaderboard
12 Qwen3-Coder-480B-A35B 7.70% Jul 2025 Official leaderboard
13 GPT-4o [snapshot unspecified] 4.40% Official leaderboard
#ModelScoreSettingDateSource
1 Seed2.1 Pro 65.8% Jun 2026 Lab model card
2 Seed2.0 Pro 60.6% Feb 2026 Lab model card
3 Seed1.8 38.2% Dec 2025 Lab model card
4 o4-mini 35.5% high Apr 2025 Official leaderboard
5 DeepSeek-R1 May 2025 22.3% May 2025 Official leaderboard
6 Qwen3-235B-A22B 17.6% Apr 2025 Official leaderboard
7 Qwen3-32B 16.3% Apr 2025 Official leaderboard
8 GPT-4.1 10.5% Apr 2025 Official leaderboard
9 Qwen3-8B 10% Apr 2025 Official leaderboard
10 Kimi K2 Sep 2025 9.80% Sep 2025 Official leaderboard
11 DeepSeek-V3 Mar 2025 8.50% Mar 2025 Official leaderboard
12 Qwen3-Coder-480B-A35B 7.70% Jul 2025 Official leaderboard

Labs report scores for 3 models in their cards. Switch the scores above to rank them together.

Number one over time 4 models have held number one with claims included since its release in August 2025

Lab claims count from the day the card came out, independent runs from the model’s release. We draw one row each for the benchmark’s own leaderboard and what labs claim in their cards.

OpenAI ByteDance Seed
Own leaderboard Not tested since Sep 2025
o4-mini 35.5%
Lab claims Not tested since Jun 2026
Seed2.1 Pro 65.8%

Sources: Official AetherCode leaderboard and labs’ model cards

Scores over time

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

On the benchmark’s own leaderboard Reported by the lab in its model card Best so far
0% 20% 40% 60% 80% 100% 2025 2026 Near the ceiling (85%) Seed2.1 Pro Seed2.0 Pro Seed1.8 o4-mini GPT-4.1 0% 20% 40% 60% 80% 100% 2025 2026 Near the ceiling (85%) Seed2.1 Pro Seed1.8

Sources: Official AetherCode leaderboard and labs’ model cards

Labs headline it less often now, last in February 2026

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
Feb 14, 2026 Seed2.0 Pro 60.6 AetherCode
Dec 18, 2025 Seed1.8 38.2 AetherCode

3 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
Jun 23, 2026 Seed2.1 Pro model card 65.8 AetherCode (Table 11) Capabilities
Mar 21, 2026 Seed1.8 model card 38.2 AetherCode (Table 1) Capabilities
Feb 14, 2026 Seed2.0 Pro model card 60.6 AetherCode (Table 3) Capabilities

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