Skip to content
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed
  1. Home
  2. /
  3. Compare
  4. /
  5. Claude Opus 5.5vsGPT OSS 20B
Updated Sep 2026

Claude Opus 5.5vsGPT OSS 20B

GPT OSS 20B is cheaper than Claude Opus 5.5 at $0.02/M vs $4/M input tokens.

Claude Opus 5.5 and GPT OSS 20B compared across 19 shared prompts
SpecClaude Opus 5.5GPT OSS 20B
Input price$4/M tokens$0.02/M tokens
Output price$20/M tokens$0.1/M tokens
Context window1.0M tokens131K tokens
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedSep 2026Aug 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 19 prompts both answered. Formatting stripped, words untouched.

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Claude Opus 5.5300 words
Midnight Silk Noodles Creamy, tangy peanut noodles with a gentle kick, ready faster than takeout. Serves: 2 Prep time: 5 minutes Cook time: 10 minutes Total time: 15 minutes The 7 Ingredients 8 oz (225 g) spaghetti (or any long noodle) ¼ cup creamy peanut butter 3 tablespoons soy sauce 1 tablespoon honey (or sugar) 1…
Read the full answer
GPT OSS 20B254 words
Pantry Pasta Bliss A quick, creamy, and comforting dish that turns everyday pantry staples into a satisfying meal. Ingredients (7 items) 8 oz spaghetti (or any pasta you have on hand) 2 Tbsp olive oil 3 cloves garlic, minced 1 (14.5 oz) can diced tomatoes (drained) 1 cup grated Parmesan cheese 1 tsp dried oregano Salt…
Read the full answer

Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Claude Opus 5.52,280 words
Architecture Review: Real-Time Collaborative Editor The most serious problems cluster in three areas: the sync model (client-clock LWW), cross-server propagation (per-server WebSockets with DB polling), and the CDN/auth layer, which can leak data between users. Issues are grouped by area below.
Read the full answer
GPT OSS 20B1,577 words
Below is a “code‑review” of the design you posted. I’ve broken it down into failure modes / race conditions / bottlenecks and for each one I provide a concrete fix (or set of fixes) together with the main trade‑offs you’ll pay for it.
Read the full answer

Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

Claude Opus 5.5936 words
The 3 Weakest Claims in the MindMeld AI Pitch "Decodes neural patterns into text with 94% accuracy. Works with any language, any device." (Slide 3) Why it's weak: It far exceeds the published state of the art. The best results for thought-to-text come from invasive implants.
Read the full answer
GPT OSS 20B711 words
Below are the three claims in the deck that raise the most skepticism, why they’re weak, and concrete ways to make them rock‑solid. # Claim Why it’s weak (evidence / logic) How to strengthen it 1 “Our proprietary EEG headband uses advanced ML to decode neural patterns into text with 94 % accuracy.”
Read the full answer

Michelin Star Recipe Design

Design an innovative recipe for a multi-component dish worthy of a Michelin 3-star restaurant. The recipe should feature an unusual…

Claude Opus 5.52,253 words
"Hive & Tide" Langoustine, Beeswax, White Chocolate & Oscietra Caviar, Hay-Baked Celeriac, Fermented Green Strawberry, Sea Buckthorn I. The Concept Most coastal menus celebrate the meeting of sea and land. This dish is about a stranger, quieter meeting: the meadow and the seabed, the bee and the langoustine.
Read the full answer
GPT OSS 20B1,220 words
Dish Title Celestial Tide – A Symphony of Sea and Cocoa A multi‑component plate that unites the briny, tender flesh of sea cucumber with the bittersweet depth of dark chocolate, framed by a bright citrus gel and a delicate sea‑weed foam.
Read the full answer

Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Claude Opus 5.53,435 words
The Transistor in 1920: A Counterfactual Through 1980 First, a Reality Check on the Premise A transistor "invented" in 1920 would not have changed the world in 1920. The actual 1947 transistor rested on three foundations that did not exist yet: Quantum theory of solids.
Read the full answer
GPT OSS 20B1,997 words
What would a 1920 transistor mean? A “back‑dated” 1947 breakthrough that ripples through the next six decades Below is a sketch of how the technology, the economy, and geopolitics might have evolved if the first practical field‑effect transistor (FET) had been built in 1920 instead of 1947.
Read the full answer

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Claude Opus 5.54,420 words
Contractor-Side Review of the Software Consulting Agreement Overall assessment: This agreement is heavily one-sided. Nearly every clause shifts risk, cost, or control to the Contractor, and several provisions interact to create compounding exposure.
Read the full answer
GPT OSS 20B1,672 words
Below is a point‑by‑point review of the contract. For each clause I identify: What makes it exploitable for the contractor. How to re‑write it so the contractor is protected. The legal principle(s) that justify the change.
Read the full answer
Our Verdict
Claude Opus 5.5
Claude Opus 5.5
GPT OSS 20B
GPT OSS 20BRunner-up

Not enough votes to call it. On the specs, Claude Opus 5.5 has the edge: newer, bigger context window.

GPT OSS 20B costs 200x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 5.5
Input
$4.00
Output
$20.00
GPT OSS 20B
Input
$0.02
200× cheaper
Output
$0.10
200× cheaper

GPT OSS 20B is cheaper on both: 200× input, 200× output.

Where to run it

15 hosts, cheapest first

Claude Opus 5.54 hosts
HostInOutContextUptime
Amazon Bedrock$4.00 in·$20.00 out·1M·99.8% upAzure AI Foundry$4.00 in·$20.00 out·1M·100% upAnthropic$4.00 in·$20.00 out·1M·100% upGoogle Vertex AI$4.00 in·$20.00 out·1M·100% up
GPT OSS 20B11 hosts
HostInOutContextUptime
DDarkbloomfp8$0.02 in·$0.09 out·131k·99.7% upAAkashMLfp4$0.02 in·$0.10 out·131k·99.1% upDDekaLLMbf16$0.03 in·$0.14 out·131k·99.2% upCCoreWeavefp4$0.03 in·$0.13 out·131k·99.9% upDDeepInfrabf16$0.03 in·$0.14 out·131k·100% upPParasailfp4$0.03 in·$0.15 out·131k·99.7% up
5 more hostsFewer hosts
NNovitafp4$0.04 in·$0.15 out·131k·98.5% upSSiliconFlowfp8$0.04 in·$0.18 out·131k·96.4% upAmazon Bedrock$0.07 in·$0.15 out·131k·97.9% upGroq$0.07 in·$0.30 out·131k·98.5% upGoogle Vertex AIdegraded$0.07 in·$0.25 out·131k·97.1% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Claude Opus 5.5 is developed by Anthropic while GPT OSS 20B is developed by OpenAI. Claude Opus 5.5 has a 1.0M token context window vs GPT OSS 20B's 131K. You can compare their actual outputs across 19 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 5.5 and GPT OSS 20B each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 19 challenges so you can judge which fits your needs best.

Claude Opus 5.5 costs $4/M input tokens and GPT OSS 20B costs $0.02/M input tokens. GPT OSS 20B is $3.98/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Claude Opus 5.5 and GPT OSS 20B across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

Keep exploring

More comparisons

Against the newest arrivals

Claude Opus 5.5 logoSolar Mini 4 logo
Claude Opus 5.5 vs Solar Mini 4Landed Sep 2026
GPT OSS 20B logoQwen3.8 Max Prime logo
GPT OSS 20B vs Qwen3.8 Max PrimeLanded Sep 2026
Claude Opus 5.5 logoGLM 5.3 Prime logo
Claude Opus 5.5 vs GLM 5.3 PrimeLanded Sep 2026
GPT OSS 20B logoQwen3.8 Omni Flash logo
GPT OSS 20B vs Qwen3.8 Omni FlashLanded Sep 2026
Claude Opus 5.5 logoCommand A+ logo
Claude Opus 5.5 vs Command A+Landed Sep 2026
GPT OSS 20B logoGPT-6 Luna Pro logo
GPT OSS 20B vs GPT-6 Luna ProLanded Sep 2026
Claude Opus 5.5 logoGPT-6 Sol Pro logo
Claude Opus 5.5 vs GPT-6 Sol ProLanded Sep 2026
GPT OSS 20B logoGPT-6 Luna logo
GPT OSS 20B vs GPT-6 LunaLanded Sep 2026

Same lab, same size, long tail

Claude Opus 5.5 logoClaude Opus 4.6 logo
Claude Opus 5.5 vs Claude Opus 4.6Same lab
Claude Opus 5.5 logoClaude Fable 5.1 logo
Claude Opus 5.5 vs Claude Fable 5.1Same lab
GPT OSS 20B logoGPT OSS 120B logo
GPT OSS 20B vs GPT OSS 120BVersion compare
GPT OSS 20B logoGPT-6 Sol Pro logo
GPT OSS 20B vs GPT-6 Sol ProSame lab
Claude Opus 5.5 logoDeepSeek V3.2 logo
Claude Opus 5.5 vs DeepSeek V3.2Same size
Claude Opus 5.5 logoDeepSeek V3.2 Exp logo
Claude Opus 5.5 vs DeepSeek V3.2 ExpSame size
Claude Opus 5.5 logoDeepSeek V3.2 Speciale logo
Claude Opus 5.5 vs DeepSeek V3.2 SpecialeSame size
Claude Opus 5.5 logoDeepSeek V4 Flash logo
Claude Opus 5.5 vs DeepSeek V4 FlashSame size

Model pages

Claude Opus 5.5 logo
Claude Opus 5.519 outputs, specs and price
GPT OSS 20B logo
GPT OSS 20B54 outputs, specs and price
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed