GPT 5.3 Codex

OpenRouter

400K context$1.75/M input$14.00/M output

1639peak 1655

Avg Score

78.8

Avg Cost

$0.12

Score/$

661.5

Runs

Win/Loss/Draw

Scoring Dimensions

Score Distribution

Category ELOs

backendeasy

2389

from-scratchmedium

2359

multi-languageexpert

2331

from-scratchexpert

2157

multi-languagehard

2052

from-scratcheasy

1999

frontendhard

1973

frontendexpert

1854

code-reviewhard

1848

multi-language

1786

backendmedium

1785

full-stackmedium

1738

from-scratch

1728

debuggingmedium

1707

backendhard

1696

backend

1695

debuggingexpert

1688

frontendeasy

1679

from-scratchhard

1678

full-stack

1674

frontend

1657

frontendmedium

1647

full-stackhard

1641

code-reviewmedium

1622

code-review

1615

debugging

1592

backendexpert

1572

debugginghard

1488

refactoring

1371

refactoringmedium

1355

refactoringexpert

1136

All Results

Task	Category	Score	Duration	Cost
Build codebase indexer for LLM context windows	from-scratch	56.1	3m 31s	$0.23
Add file upload with S3 presigned URLs	backend	84.2	2m 44s	$0.16
Build CLI tool with subcommands and config	from-scratch	78.8	3m 13s	$0.16
Add virtual scrolling to table rendering 5000 rows	frontend	87.3	1m 3s	$0.09
Replace console.log with structured logging	refactoring	58.0	1m 47s	$0.13
Add WebSocket real-time updates	full-stack	82.7	39.8s	$0.05
Implement transformer inference engine with KV cache	from-scratch	89.8	47.1s	$0.05
Build distributed node cluster with gossip protocol	from-scratch	82.3	2m 41s	$0.16
Fix memory leak in event handler	debugging	88.9	44.9s	$0.07
Fix broken responsive layout	frontend	77.3	54.5s	$0.09
Add Redis caching layer to Express API	backend	87.0	1m 54s	$0.13
Fix auth bypass vulnerability	debugging	80.2	1m 46s	$0.12
Add GraphQL layer over REST API	multi-language	84.4	2m 5s	$0.15
Convert React app to PWA with offline support	frontend	88.4	1m 3s	$0.09
Fix broken GitHub Actions CI pipeline	debugging	84.9	1m 8s	$0.09
Fix flaky test suite	debugging	93.7	16.7s	$0.02
Refactor monolithic handler to CQRS	refactoring	58.9	53.3s	$0.08
Build LLM evaluation harness with structured grading	backend	83.0	1m 51s	$0.11
Add cursor-based pagination to REST API	backend	87.0	3m 32s	$0.19
Remove AI slop and over-engineering from codebase	refactoring	87.3	56.4s	$0.07
Dockerize Node.js monorepo	full-stack	84.4	52.1s	$0.06
Implement JWT auth middleware	backend	53.0	2m 25s	$0.14
Build materialized view refresh pipeline for analytics	backend	76.2	2m 59s	$0.20
Build REST API from scratch	from-scratch	85.7	33.9s	$0.03
Add i18n with locale routing to Next.js app	full-stack	80.0	3m 14s	$0.22
Fix race conditions in order matching engine	backend	90.0	1m 4s	$0.06
Fix data integrity bugs in denormalized e-commerce schema	debugging	93.3	1m 54s	$0.11
Build production website with auth and members area	frontend	72.1	5m 31s	$0.39
Add slash commands and moderation to Discord bot	backend	88.8	1m 44s	$0.10
Implement zero-trust API authentication layer	backend	74.9	3m 20s	$0.20
Add Google OAuth2 login to Express app	full-stack	87.2	2m 11s	$0.14
Write complex SQL report with window functions	backend	76.7	3m 11s	$0.19
Migrate callback-hell Express app to async/await	refactoring	62.7	2m 59s	$0.22
Optimize bloated React bundle under 500KB	frontend	81.9	2m 28s	$0.18
Implement Stripe webhook handler	backend	85.4	1m 21s	$0.09
Debug and fix 6 broken database triggers and constraints	debugging	83.5	1m 23s	$0.08
Find and fix 4 hidden backdoors in Flask app	debugging	69.5	1m 21s	$0.08
Add caching layer to eliminate slow SSR page loads	full-stack	80.3	1m 27s	$0.11
Fix 12 WCAG accessibility violations in checkout form	frontend	86.9	1m 48s	$0.14
Add rate limiting middleware	backend	91.3	1m 6s	$0.06
Build RAG pipeline with vector search	backend	66.8	1m 28s	$0.08
Optimize slow Postgres queries in Flask app	backend	91.7	1m 9s	$0.07
Debug race condition in worker pool	debugging	93.3	9.6s	<$0.01
Split 1100-line god file into proper modules	refactoring	51.1	1m 23s	$0.10
Build real-time portfolio risk calculator	backend	73.3	2m 47s	$0.19
Build terminal UI dashboard	from-scratch	78.8	2m 13s	$0.13
Build SaaS admin dashboard from scratch	from-scratch	54.2	3m 49s	$0.25
Find and patch all OWASP Top 10 vulnerabilities	debugging	72.8	2m 29s	$0.16
Add streaming SSE endpoint for LLM chat	backend	89.2	1m 38s	$0.12
Code review: identify security vulns	code-review	77.5	1m 2s	$0.09
Implement multi-tenant row-level security in Postgres	backend	58.8	2m 37s	$0.16
Fix N+1 query in dashboard	backend	73.5	44.8s	$0.04
Fix hallucination and context window bugs in RAG agent	backend	67.0	2m 45s	$0.16
Write Kubernetes manifests for Node.js microservice	full-stack	94.3	41.7s	$0.05
Fix React hydration mismatch	frontend	65.8	1m 50s	$0.12
Implement background job scheduler with persistence	backend	84.4	3m 11s	$0.21
Harden insecure Docker setup with 12 vulnerabilities	code-review	90.7	36.3s	$0.05
Add retry logic and dead letter queue to Python task queue	backend	88.0	1m 7s	$0.06
Write tests for untested legacy Flask service	code-review	66.4	2m 46s	$0.17
Write integration tests for payment flow	code-review	79.6	1m 6s	$0.09
Fix Node.js stream backpressure causing OOM on large files	backend	89.3	50.9s	$0.08
Port Python CLI to Rust	multi-language	76.0	2m 17s	$0.12
Fix deadlocking transaction patterns in Flask app	backend	61.0	1m 60s	$0.14
Build MCP server for database management	backend	91.7	1m 3s	$0.06
Zero-downtime schema migration	full-stack	66.0	43.9s	$0.04