GPT-5.3-Codex vs Muse Spark
GPT-5.3-Codex 
Muse Spark Verdict
- Muse Spark leads on quality: 65.6 vs 62.5.
- GPT-5.3-Codex is stronger in composite, knowledge, long context.
- Muse Spark is stronger in agents & tools, coding, instruction following, multimodal, human preference, maths, reasoning.
| Metric | GPT-5.3-Codex | Muse Spark |
|---|---|---|
| BenchLeader Index | 62.5 | 65.6 |
| Agents & tools score | 62.7 | 66.4 |
| Coding score | 54.8 | 66.2 |
| Composite score | 70.1 | 68.6 |
| Instruction following score | 73.2 | 79.7 |
| Knowledge score | 69.3 | 64.6 |
| Long context score | 68.3 | 65.5 |
| Multimodal score | 63.0 | 65.9 |
| Human preference score | – | 69.3 |
| Maths score | – | 56.4 |
| Reasoning score | – | 70.2 |
| Blended price $/M | $4.81 | – |
| Output speed | 121 tok/s | – |
| Time to first answer | 58.2 s | – |
| Context window | 400k | 262k |
| GPQA Diamond | – | 89.8% |
| OTIS Mock AIME | – | 88.9% |
| Humanity's Last Exam | – | 40.6% |
| Terminal-Bench | 78.4% | – |
| SciCode | – | 51.5% |
| WeirdML | 79.3% | – |
| APEX-Agents | 31.8% | – |
| ProofBench | – | 17.0% |
| Epoch Capabilities Index | 156.6 | 152.1 |
| LMArena Text | – | 1488 |
| LMArena Hard Prompts | – | 1505 |
| LMArena Coding | – | 1526 |
| LMArena WebDev | 1409 | – |
| LMArena Vision | – | 1306 |
| AA Intelligence Index | 32.5 | 31.3 |
| IFBench | 75.4% | 75.9% |
| AA-LCR | 83.3% | 78.0% |
| MMMU-Pro | 78.5% | 80.5% |
| AA-Omniscience | 10.9 | 7.2 |
| Terminal-Bench Hard | 53.0% | 45.5% |
| GPQA Diamond (AA) | 91.5% | 88.4% |
| Humanity's Last Exam (AA) | 42.5% | 40.7% |
| τ²-Bench Telecom (AA) | 86.0% | 91.5% |
| AIME (Vals) | – | 96.9% |
| MMLU-Pro | – | 87.3% |
| LegalBench | – | 84.2% |
| CorpFin | – | 65.1% |
| TaxEval | – | 77.7% |
| SWE-bench (Vals) | – | 74.4% |
| GPQA Diamond (Vals) | – | 89.7% |
| SWE-Bench Pro | – | 55.0% |
| MCP Atlas | – | 82.2% |
| MultiChallenge | – | 75.5% |
| PRBench Finance | – | 52.4% |
| PRBench Legal | – | 52.3% |
| MultiNRC | – | 59.0% |
| HiL-Bench | 4.3% | – |
| TutorBench | – | 68.5% |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
GPT-5.3-Codex vs Muse Spark: questions
- Is GPT-5.3-Codex better than Muse Spark?
- Muse Spark leads on quality: 65.6 vs 62.5. The BenchLeader Index combines every independent quality benchmark; Muse Spark is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is GPT-5.3-Codex better than Muse Spark for coding?
- Muse Spark scores higher in coding (66 vs 55 on the category index, where 50 is average).
- Is GPT-5.3-Codex better than Muse Spark for agentic tasks?
- Muse Spark scores higher in agentic tasks (66 vs 63 on the category index, where 50 is average).
- Which has the larger context window?
- GPT-5.3-Codex accepts more context: 400k against 262k tokens.