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Model usage data, product updates, and research reports. One email each week.

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OpenAI: gpt-oss-20b

openai/gpt-oss-20b

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gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license. It uses a Mixture-of-Experts (MoE) architecture with 3.6B active parameters per forward pass, optimized for lower-latency inference and deployability on consumer or single-GPU hardware. The model is trained in OpenAI’s Harmony response format and supports reasoning level configuration, fine-tuning, and agentic capabilities including function calling, tool use, and structured outputs.

Modalities

In / Out Price

$0.02 / $0.10per 1M

Context

131K

Released

Aug 5, 2025

Knowledge Cutoff

Jun 2024

Compare
ProvidersPricingPerformanceUptimeBenchmarksAppsActivityFAQExplore

Providers

Different companies host the same model. OpenRouter routes your request to one of them based on the routing mode you pick — Balanced (price + speed), Nitro (fastest), Floor (cheapest), or Exacto (highest tool-calling accuracy).

Pricing

The average price customers actually pay for this model, next to the prices providers post. Caching and discounts mean the price actually paid is often well below the listed one.

Performance

Throughput is how fast the model writes (tokens per second — higher is better). Latency is total round-trip time (lower is better). TTFT is time-to-first-token — how long before you see anything appear (lower is better).

Uptime

Uptime is the percentage of the past 3 days that at least one provider was responding to requests. Availability is the percentage of time that inference was successfully served. OpenRouter continuously monitors and uses the next-best provider when one returns an error.

Benchmarks

Scores on standardized evaluations. Higher percentages are better — and rank percentile shows where this model lands among all models on OpenRouter.

Benchmark score summary for OpenAI: gpt-oss-20b (Artificial Analysis and Design Arena)
SourceBenchmarkScore
Artificial Analysisgpt-oss-20b (high) Intelligence Index9.0
Artificial Analysisgpt-oss-20b (high) Coding Index20.7
Artificial Analysisgpt-oss-20b (high) Agentic Index1.4
Artificial Analysisgpt-oss-20b (high) GPQA Diamond68.8%
Artificial Analysisgpt-oss-20b (high) HLE11.0%
Artificial Analysisgpt-oss-20b (high) IFBench65.1%
Artificial Analysisgpt-oss-20b (high) τ²-Bench Telecom60.2%
Artificial Analysisgpt-oss-20b (high) AA-LCR34.7%
Artificial Analysisgpt-oss-20b (high) GDPval-AA0.7%
Artificial Analysisgpt-oss-20b (high) CritPt1.4%
Artificial Analysisgpt-oss-20b (high) SciCode38.9%
Artificial Analysisgpt-oss-20b (high) Terminal-Bench Hard10.6%
Artificial Analysisgpt-oss-20b (high) AA-Omniscience Accuracy16.0%
Artificial Analysisgpt-oss-20b (high) AA-Omniscience Non-Hallucination Rate5.9%
Artificial Analysisgpt-oss-20b (low) GPQA Diamond61.1%
Artificial Analysisgpt-oss-20b (low) HLE5.3%
Artificial Analysisgpt-oss-20b (low) IFBench57.8%
Artificial Analysisgpt-oss-20b (low) τ²-Bench Telecom50.3%
Artificial Analysisgpt-oss-20b (low) AA-LCR31.0%
Artificial Analysisgpt-oss-20b (low) CritPt0.0%
Artificial Analysisgpt-oss-20b (low) Terminal-Bench Hard4.5%
Artificial Analysisgpt-oss-20b (low) AA-Omniscience Accuracy15.1%
Artificial Analysisgpt-oss-20b (low) AA-Omniscience Non-Hallucination Rate13.3%
Design ArenaGPT OSS 20B Models Arena Data Visualization Elo946
Design ArenaGPT OSS 20B Models Arena Website Elo865

Apps

Public apps that send the most traffic to this model. Good signal for what real production workloads look like — and a hint at which use cases this model is best suited for.

Activity

Token volume and request traffic to this model over time.

Quick Start

Drop-in code to call this model. OpenRouter's API is OpenAI-compatible — most SDKs work by just swapping the base URL. The only thing that changes between models is the model slug below.

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Throughput

253tok/s

P50, best across providers

Latency

0.11s

P50, best provider

AutoExacto Benchmarks
GPQA DiamondTAU-BenchPhala66.7%--SiliconFlow62.3%--Fireworks61.7%--Darkbloom63.4%57.2%Amazon Bedrock66.4%50.7%Amazon Bedrock (EU)64.5%49.8%
+6 more providers
Uptime (3d)The model was reachable. Request routed to a provider.

100.00%

Availability (3d)The model returned inference from any provider. Errors and empty responses count against it.

98.71%

Availability over the last 3 days

Last 72 hours
Availability 98.71%
3 Days Ago2 Days AgoYesterdayNow

Availability over the last 24 hours

OpenRouter Availability
97.73%
Without Routing
91.69%

When an error occurs in an upstream provider, we can recover by routing to another healthy provider, if your request filters allow it. You can access per-provider uptime data programmatically through the Endpoints API. Learn more about our load balancing and customization options.

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Frequently asked questions

gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license. It uses a Mixture-of-Experts (MoE) architecture with 3.6B active parameters per forward pass, optimized for lower-latency inference and deployability on consumer or single-GPU hardware.

gpt-oss-20b costs $0.02/M input tokens and $0.10/M output tokens.

gpt-oss-20b has a 131,072 token context window. It supports up to 32,768 completion tokens.

Yes. gpt-oss-20b accepts tools and tool_choice for function calling on 8 of the 12 providers serving it, and requests that send tools are routed to those providers. It also supports structured outputs via a JSON schema in response_format.

gpt-oss-20b is served by 12 providers on OpenRouter: Darkbloom, AkashML, DekaLLM, CoreWeave, DeepInfra, Parasail, NovitaAI, SiliconFlow and 4 more. Requests are routed to the best available provider, with automatic failover to the others, and you can pin or exclude providers with provider routing.

gpt-oss-20b was released on August 5, 2025. Its knowledge cutoff is June 30, 2024.

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