Claude and GPT are the two heaviest production-deployed model families in 2026. Both work for almost everything — but they're not interchangeable. This is a sharp side-by-side from the perspective of someone who has run both behind real coding agents (Claude Code, Cline, OpenClaw, Cursor, Codex CLI) for thousands of hours.
The agent default — cleanest tool-use, best long-chain coherence.
Frontier reasoning + native multimodal + broadest world knowledge.
Claude wins clearly. Tool-call cleanliness, diff format reliability, and long-chain coherence matter more here than raw reasoning. Every major agent (Claude Code, Cline, Aider, OpenCode, Goose) defaults to Claude Sonnet for a reason.
GPT-5.5 leads on math olympiad, novel scientific reasoning, and obscure-fact recall. If your task is 'solve a hard puzzle once' rather than 'execute a long workflow', GPT pulls ahead.
GPT-5.5 has better vision accuracy and native audio. Claude vision works but Anthropic hasn't shipped audio/image-gen yet.
Both top out around 200-256k. For really long docs (1M+), Gemini 3 Pro beats both. Within their ranges they're equivalent for summarization and Q&A.
Direct: Opus is cheaper on input ($5 vs $4 GPT-5.5 — Opus wins) but more expensive on output ($25 vs $32 — Opus loses on long generation). Net: depends on use case. Through claudeapi.cheap's 80% Pro discount, both come down to ~$1/M input, $5-6.40/M output — both highly affordable.
Both support streaming + tool calling. Claude's tool-call format is more consistent — fewer error-recovery loops in real agent code.
If you're building an autonomous coding agent or anything tool-heavy, default to Claude — start with Sonnet 4.6, escalate to Opus 4.7 for hard work. If you're solving one-off reasoning puzzles, summarizing massive docs with vision, or need broadest world knowledge, reach for GPT-5.5 or GPT-5.3 Codex. Smart teams run both and route per task — both are 70-80% off through claudeapi.cheap with one key.
claudeapi.cheap gives you both at 70-80% off list, through the same sk-cc-... key. Test Claude and GPT side-by-side with no separate signups, no separate billing. Drop-in compatible with Anthropic SDK + OpenAI SDK.
Get a free API keyIt depends on the model tier and the input/output ratio. Claude Opus 4.7 has cheaper input ($5/M vs GPT-5.5 $4/M — actually GPT wins on input) but cheaper output ($25/M vs GPT-5.5 $32/M — Claude wins on output). Through claudeapi.cheap Pro (80% off), both flagship tiers are $0.80-$1.00 per 1M input — close enough that you should pick on capability, not cost.
Yes, and you should. Many production setups use Claude Sonnet for the main agent loop and GPT-5.3 Codex for one-off code generation, or vice versa. With claudeapi.cheap, both vendors are accessed via one sk-cc-... API key — no juggling.
Mostly. Both support streaming, tool calling, structured outputs (JSON mode), system prompts, vision (with restrictions). GPT supports image and audio generation; Claude doesn't yet. Claude has prompt caching with a 90% read discount; OpenAI's prompt caching is automatic but with smaller discounts.
Claude wins for autonomous coding agents (multi-turn, file edits, repo work). GPT-5.3 Codex wins for one-shot code generation tasks. SWE-bench leaderboard fluctuates between them month-to-month.