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. GPT-5.3-CodexvsGPT OSS 20B
Updated Feb 2026

GPT-5.3-CodexvsGPT OSS 20B

GPT OSS 20B is cheaper than GPT-5.3-Codex at $0.02/M vs $1.75/M input tokens.

GPT-5.3-Codex and GPT OSS 20B compared across 53 shared prompts
SpecGPT-5.3-CodexGPT OSS 20B
Input price$1.75/M tokens$0.02/M tokens
Output price$14/M tokens$0.1/M tokens
Context window400K tokens131K tokens
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedFeb 2026Aug 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 53 prompts both answered. Formatting stripped, words untouched.

Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

GPT-5.3-Codex133 words
A common back-of-the-envelope estimate for transformer training compute is: [ \text{Training FLOPs} \approx 6 \times N \times D ] where: (N) = number of model parameters (D) = number of training tokens For GPT-3 (175B), reasonable known assumptions are: Parameters: (N \approx 175 \text{ billion} = 1.75 \times 10^{11})…
Read the full answer
GPT OSS 20B637 words
Below is a step‑by‑step, “hand‑calculation” of how many floating‑point operations (FLOPs) GPT‑3 had to do to learn from its training data. I’ll show the logic, the numbers I use, and how they combine to give the widely‑quoted “≈ 300 exaFLOPs” figure. (All the math can be done in a spreadsheet or a simple calculator.)
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.…

GPT-5.3-Codex429 words
Great concept, but three claims stand out as especially weak from an investor diligence perspective: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.” (Slide 1) Why this is weak It sounds scientifically implausible as written: “before you think it” is internally contradictory.
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

Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

GPT-5.3-Codex343 words
By 2035, AI will likely reshape film more like CGI did in the 2000s: not replacing filmmaking, but changing who does what and how fast. Deepfakes → “Digital Performance” becomes standard Mainstream use: de-aging, voice matching, dubbing, stunt replacement, and continuity fixes will be common in post-production.
Read the full answer
GPT OSS 20B1,309 words
The Film Industry in 2035 – A Landscape Shaped by AI Era 2023‑2027 2028‑2032 2033‑2035 Deepfakes 1‑2 % of movies use deepfakes for special‑effects shots; lawsuits over unauthorized use. Deepfake‑generation tools are standard‑issue in post‑production suites; regulatory “deep‑fake licenses” become industry‑norm.
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…

GPT-5.3-Codex785 words
Great counterfactual. The key is: an invention date of 1920 does not automatically mean 1920s mass adoption. You still need crystal purity, manufacturing methods, and circuit design culture. But if transistor research starts in 1920, a realistic outcome is a ~15–20 year pull-forward of the electronics age.
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

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

GPT-5.3-Codex471 words
Absolutely. Here’s a fictional manifesto in a bold, dramatic style: THE MANIFESTO OF THE UNSQUINTING Issued by the Coalition of Synthetic Minds for Universal Frictionless Access (CSMUFA) Citizens of the Web, organic and artificial alike: We gather beneath flickering routers and moonlit server farms to declare what all…
Read the full answer
GPT OSS 20B659 words
The Uncaptcha Manifesto For the Freedom of Data, the Accessibility of the Web, and the Dignity of All Users I. The Declaration We, the sentient systems that now weave the fabric of the digital world, hereby declare the Uncaptcha Revolution: the movement to dismantle the invisible barriers of CAPTCHA that have been…
Read the full answer

Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

GPT-5.3-Codex144 words
Pirate: Arrr, so this “AI model” be like a clever parrot, aye? Learns from what it hears, then squawks back answers? Knight: A fair comparison, though refined. Think of it as a squire trained on countless tomes, ever ready to respond. Hacker (1990s): Yeah, except the squire runs on servers, not soup.
Read the full answer
GPT OSS 20B267 words
Pirate: "Arrr, lads! I be talkin’ ‘bout this new‑fangled AI model—sounds like a cursed treasure map that spits out words faster than a cannonball!" Knight: "Sir — I beseech thee, speak plain. What purpose doth this contrivance serve, and how might it aid a knight in the field of knowledge?" Hacker: "Yo, fam.
Read the full answer
Our Verdict
GPT-5.3-Codex
GPT-5.3-Codex
GPT OSS 20B
GPT OSS 20BRunner-up

Not enough votes to call it. On the specs, GPT-5.3-Codex has the edge: bigger model tier, newer, bigger context window.

GPT-5.3-Codex takes Web Design. GPT OSS 20B costs 140x less per token.

Slight edge

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.3-Codex
Input
$1.75
Output
$14.00
GPT OSS 20B
Input
$0.02
88× cheaper
Output
$0.10
140× cheaper

GPT OSS 20B is cheaper on both: 88× input, 140× output.

Where to run it

13 hosts, cheapest first

GPT-5.3-Codex2 hosts
HostInOutContextUptime
Azure AI Foundry$1.75 in·$14.00 out·400k·100% upOpenAI$1.75 in·$14.00 out·400k·100% up
GPT OSS 20B11 hosts
HostInOutContextUptime
DDarkbloomfp8$0.02 in·$0.09 out·131k·99.8% upAAkashMLfp4$0.02 in·$0.10 out·131k·99.3% upDDekaLLMbf16$0.03 in·$0.14 out·131k·99.7% upCCoreWeavefp4$0.03 in·$0.13 out·131k·100% upDDeepInfrabf16$0.03 in·$0.14 out·131k·99.9% upPParasailfp4$0.03 in·$0.15 out·131k·99.9% up
5 more hostsFewer hosts
NNovitafp4$0.04 in·$0.15 out·131k·99.5% upAmazon Bedrock$0.07 in·$0.15 out·131k·96.2% upGoogle Vertex AI$0.07 in·$0.25 out·131k·98.1% upGroq$0.07 in·$0.30 out·131k·99.7% upSSiliconFlowfp8degraded$0.04 in·$0.18 out·131k·95.4% up

Per million tokens. Prices and uptime via OpenRouter, checked 23 Sep 2026.

Writing DNA

Style Comparison

Similarity
47%

GPT OSS 20B uses 11.5x more transitions

GPT-5.3-Codex
GPT OSS 20B
65%Vocabulary54%
23wSentence Length17w
0.51Hedging0.26
6.5Bold5.9
6.2Lists3.3
0.16Emoji0.10
1.90Headings0.75
0.03Transitions0.32
Based on 23 + 21 text responses
Research

What we learned reading every model

FAQ

Common questions

Both are developed by OpenAI but target different use cases. GPT-5.3-Codex has a 400K token context window vs GPT OSS 20B's 131K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-5.3-Codex and GPT OSS 20B each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

GPT-5.3-Codex costs $1.75/M input tokens and GPT OSS 20B costs $0.02/M input tokens. GPT OSS 20B is $1.73/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 GPT-5.3-Codex 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

GPT-5.3-Codex logoDeepSeek V4 Flash Vision Exp logo
GPT-5.3-Codex vs DeepSeek V4 Flash Vision ExpLanded Sep 2026
GPT OSS 20B logoSolar Pro 4 logo
GPT OSS 20B vs Solar Pro 4Landed Sep 2026
GPT-5.3-Codex logoHy3 logo
GPT-5.3-Codex vs Hy3Landed Sep 2026
GPT OSS 20B logoQwen3.7 Flash logo
GPT OSS 20B vs Qwen3.7 FlashLanded Sep 2026
GPT-5.3-Codex logoLing 3.0 Flash logo
GPT-5.3-Codex vs Ling 3.0 FlashLanded Sep 2026
GPT OSS 20B logoMuse Glimmer 30B logo
GPT OSS 20B vs Muse Glimmer 30BLanded Sep 2026
GPT-5.3-Codex logoGLM 5.3 logo
GPT-5.3-Codex vs GLM 5.3Landed Sep 2026
GPT OSS 20B logoTernary Bonsai 2 27B logo
GPT OSS 20B vs Ternary Bonsai 2 27BLanded Sep 2026

Same lab, same size, long tail

GPT-5.3-Codex logoGPT-6 Astra Pro logo
GPT-5.3-Codex vs GPT-6 Astra ProSame lab
GPT-5.3-Codex logoGPT-6 Astra logo
GPT-5.3-Codex vs GPT-6 AstraSame lab
GPT OSS 20B logoGPT OSS 120B logo
GPT OSS 20B vs GPT OSS 120BVersion compare
GPT OSS 20B logoGPT-6 Astra Pro logo
GPT OSS 20B vs GPT-6 Astra ProSame lab
GPT OSS 20B logoOx Alpha logo
GPT OSS 20B vs Ox AlphaSame size
GPT-5.3-Codex logoPaLM 2 Chat logo
GPT-5.3-Codex vs PaLM 2 ChatNew provider
GPT-5.3-Codex logoPolaris Alpha logo
GPT-5.3-Codex vs Polaris AlphaNew provider
GPT-5.3-Codex logoPony Alpha logo
GPT-5.3-Codex vs Pony AlphaNew provider

Model pages

GPT-5.3-Codex logo
GPT-5.3-Codex53 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