# Composer 2 Fast vs GPT-OSS 20B

> Side-by-side benchmark comparison for Composer 2 Fast and GPT-OSS 20B across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/composer-2-fast-vs-gpt-oss-20b
- Last updated: September 10, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Composer 2 Fast and GPT-OSS 20B share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Composer 2 Fast has the larger published context window at 200K.

## Model Snapshot

| Property | Composer 2 Fast | GPT-OSS 20B |
|----------|----------|----------|
| Creator | Cursor | OpenAI |
| Type | Proprietary | Open Weight |
| Reasoning | Reasoning | Non-Reasoning |
| Context | 200K | 128K |
| Independent public score (not head-to-head) | null | 40.73 |
| Benchmarks Covered | 1 | 1 |
| Pricing (input/output) | N/A | $0.00 / $0.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Composer 2 Fast public-lane score: Coming soon
- GPT-OSS 20B public-lane score: 36.3 (Estimated · #131/152)

### Coding

- Winner: Insufficient shared evidence
- Composer 2 Fast public-lane score: Coming soon
- GPT-OSS 20B public-lane score: 38.3 (Estimated · #123/151)

| Benchmark | Composer 2 Fast | GPT-OSS 20B | Winner |
|-----------|-----------|-----------|--------|
| React Native Evals | 94.9% | 71% | Composer 2 Fast |

### Reasoning

- Winner: Insufficient shared evidence
- Composer 2 Fast public-lane score: Coming soon
- GPT-OSS 20B public-lane score: 44.9 (Unranked · 2 rankable rows)

### Knowledge

- Winner: Insufficient shared evidence
- Composer 2 Fast public-lane score: Coming soon
- GPT-OSS 20B public-lane score: 39.1 (Estimated · #139/183)

### Instruction Following

- Winner: Insufficient shared evidence
- Composer 2 Fast public-lane score: Coming soon
- GPT-OSS 20B public-lane score: 79.2 (#55/123)

## FAQ

### Is there enough evidence to pick between Composer 2 Fast and GPT-OSS 20B?

Not yet. The models share only 1 sourced benchmark row, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [Composer 2 Fast vs Composer 2.5](/compare/composer-2-5-vs-composer-2-fast)
- [GPT-OSS 20B vs Composer 2.5](/compare/composer-2-5-vs-gpt-oss-20b)
- [Composer 2 Fast vs Composer 2](/compare/composer-2-vs-composer-2-fast)
- [GPT-OSS 20B vs Composer 2](/compare/composer-2-vs-gpt-oss-20b)

## Explore More

- [Composer 2 Fast profile](/models/composer-2-fast)
- [GPT-OSS 20B profile](/models/gpt-oss-20b)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)