# GPT-5.3 Codex vs Qwen3.5 Flash

> Side-by-side benchmark comparison for GPT-5.3 Codex and Qwen3.5 Flash across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-3-codex-vs-qwen3-5-flash
- Last updated: September 29, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.3 Codex and Qwen3.5 Flash share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Qwen3.5 Flash has the lower published output-token price.
- Qwen3.5 Flash has the larger published context window at 1M.

## Model Snapshot

| Property | GPT-5.3 Codex | Qwen3.5 Flash |
|----------|----------|----------|
| Creator | OpenAI | Alibaba |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 400K | 1M |
| Independent public score (not head-to-head) | 61.81 | 45.47 |
| Benchmarks Covered | 10 | 6 |
| Pricing (input/output) | $1.75 / $14.00 | $0.10 / $0.40 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 54.1 (Estimated · #34/117)
- Qwen3.5 Flash public-lane score: Coming soon

| Benchmark | GPT-5.3 Codex | Qwen3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 77.3% | Coming soon | Coming soon |
| OSWorld-Verified | 64.7% | Coming soon | Coming soon |
| Gert Labs | 57.47% | Coming soon | Coming soon |
| JobBench | 33.7% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 55.5 (Supported · #29/143)
- Qwen3.5 Flash public-lane score: 26.5 (Estimated · #103/143)

| Benchmark | GPT-5.3 Codex | Qwen3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 85% | Coming soon | Coming soon |
| SWE-bench Pro | 56.8% | Coming soon | Coming soon |
| SWE-Rebench | 58.2% | Coming soon | Coming soon |
| Vibe Code Bench | 61.77% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 87.3% | 83.3% | GPT-5.3 Codex |
| SWE-bench (Vals) | 78.0% | 64.4% | GPT-5.3 Codex |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 79.6 (Unranked · 2 rankable rows)
- Qwen3.5 Flash public-lane score: Coming soon

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 76.7 (Unranked · 1 rankable row)
- Qwen3.5 Flash public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 63.8 (Estimated · #31/169)
- Qwen3.5 Flash public-lane score: 43.1 (Estimated · #85/169)

| Benchmark | GPT-5.3 Codex | Qwen3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| GPQA Diamond (Vals) | Coming soon | 82.8% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 84.1% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: 91.2 (#14/124)
- Qwen3.5 Flash public-lane score: Coming soon

### Mathematics

- Winner: Insufficient shared evidence
- GPT-5.3 Codex public-lane score: Coming soon
- Qwen3.5 Flash public-lane score: 28.4 (Unranked · 2 rankable rows)

| Benchmark | GPT-5.3 Codex | Qwen3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | Coming soon | 6.207% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 0.000% | Coming soon |

## FAQ

### Is there enough evidence to pick between GPT-5.3 Codex and Qwen3.5 Flash?

Not yet. The models share only 2 sourced benchmark rows, 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

- [GPT-5.3 Codex vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-vs-gpt-5-3-codex-spark)
- [Qwen3.5 Flash vs GPT-5.3-Codex-Spark](/compare/gpt-5-3-codex-spark-vs-qwen3-5-flash)
- [GPT-5.3 Codex vs GPT-6 Astra](/compare/gpt-5-3-codex-vs-gpt-6-astra)
- [Qwen3.5 Flash vs GPT-6 Astra](/compare/gpt-6-astra-vs-qwen3-5-flash)

## Explore More

- [GPT-5.3 Codex profile](/models/gpt-5-3-codex)
- [Qwen3.5 Flash profile](/models/qwen3-5-flash)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)