GPT-5.3 Codex vs gpt-oss-20b
At a Glance
| Compare |  GPT-5.3 CodexOpenAI | gpt-oss-20bOpenAI |
|---|---|---|
| Pricing and Limits | ||
| Input priceFrom · USD / 1M tokens | $1.75Openai ↗ · Sep 3, 2026 | $0.030Deepinfra ↗ · Sep 22, 2026 |
| Output priceFrom · USD / 1M tokens | $14.00Openai ↗ · Sep 3, 2026 | $0.13Openrouter ↗ · Sep 22, 2026 |
| Context windowMaximum documented tokens | 400K | 131K |
| Model facts checked | Sep 3, 2026View model evidence → | Aug 28, 2026View model evidence → |
Token prices are the lowest available sourced USD rates; input and output may use different providers. Cost ranking estimates output spend on LiveBench, not a full request bill. Ranking methodology →
Available Benchmarks
Side-by-Side Facts
| Field | GPT-5.3-Codex | gpt-oss-20b |
|---|---|---|
| Developer | OpenAI | OpenAI |
| Family | Gpt 5 3 | Gpt Oss |
| Model | GPT-5.3-Codex | gpt-oss-20b |
| Version | GPT-5.3-Codex | gpt-oss-20b |
| Lifecycle | active | active |
| Released | Unknown | Unknown |
| Knowledge cutoff | 2025-08-31 | Unknown |
| Input modalities | Text, Image | Text |
| Output modalities | Text | Text |
| Context window | 400K | 131K |
| Total parameters | Unknown | 20.9B |
| Active parameters | Unknown | 3.6B |
| License | Unknown | apache-2.0 |
| Open weights | No | Yes |
| API available | Yes | Yes |
| Self-hostable | No | Yes |
| Provider access | Openai (Standard), Openrouter (Standard) | Deepinfra (Standard), Groq (Standard), Hugging Face (Standard), Openrouter (Standard), Together Ai (Serverless, Standard) |
| Capabilities | chat, generation, reasoning, structured_outputs, tools | chat, generation, reasoning, tools |
GPT-5.3 Codex Capabilities
gpt-oss-20b Capabilities
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Primary Evidence
Sources and Freshness
Questions
GPT-5.3 Codex vs gpt-oss-20b FAQs
Is GPT-5.3 Codex or gpt-oss-20b better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both GPT-5.3 Codex and gpt-oss-20b, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, GPT-5.3 Codex or gpt-oss-20b?+
GPT-5.3 Codex is $1.75 and gpt-oss-20b is $0.030 per million tokens, so gpt-oss-20b is cheaper on this metric. GPT-5.3 Codex is $14.00 and gpt-oss-20b is $0.13 per million tokens, so gpt-oss-20b is cheaper on this metric.
Which has a larger context window, GPT-5.3 Codex or gpt-oss-20b?+
GPT-5.3 Codex has the larger sourced context window. GPT-5.3 Codex supports 400K and gpt-oss-20b supports 131K.
Which performs better in benchmarks, GPT-5.3 Codex or gpt-oss-20b?+
There is no overall benchmark winner: At least two independently verified, protocol-matched benchmarks are required for an overall winner.
Can GPT-5.3 Codex or gpt-oss-20b be self-hosted?+
gpt-oss-20b is the only model in this pair currently marked as self-hostable. GPT-5.3 Codex is not marked open weight; gpt-oss-20b is open weight.
Can GPT-5.3 Codex and gpt-oss-20b understand images?+
GPT-5.3 Codex is documented with image input; gpt-oss-20b is not documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, GPT-5.3 Codex or gpt-oss-20b?+
Neither has a larger sourced maximum output. GPT-5.3 Codex is 128K and gpt-oss-20b is —.
Do GPT-5.3 Codex and gpt-oss-20b support reasoning and tool use?+
GPT-5.3 Codex: reasoning, tool calling, and image input. gpt-oss-20b: reasoning and tool calling. Feature support does not establish relative quality.
Which is available from more inference providers, GPT-5.3 Codex or gpt-oss-20b?+
GPT-5.3 Codex has 2 sourced provider routes; gpt-oss-20b has 5, so gpt-oss-20b has broader tracked availability.
Which offers better value, GPT-5.3 Codex or gpt-oss-20b?+
There is no universal value winner. Compare the input and output prices above with the matched benchmark result for your workload: cheaper tokens can be offset by different quality, token usage, latency, or provider availability.