WhichAI.todayClaude Opus 5.5
Anthropic
Pick this when the code has to be right the first time.
Skip it for simple edits and quick boilerplate where faster, cheaper models suffice.
LMArena Code 1813; 89.9% on SWE-bench Pro
Claude Opus 5.5 vs Kimi K3
Updated Nov 13, 2026. Checked daily.
The short answer
Claude Opus 5.5 ranks ahead for coding & software, writing & marketing. Kimi K3 ranks ahead for legal & long documents.
Claude Opus 5.5
2 of 3 jobs ahead
Paid plan
Kimi K3
1 of 3 jobs ahead
Free (limited)
Head to head, job by job
Each job ranks a #1, an alternative, and an open-weights pick from public leaderboards. Bars compare the two scores on that job's own signal.
Which one should you pick?
Kimi K3
Moonshot AI
Pick this when the code cannot leave your own machines.
Skip self-hosting if you lack multi-GPU cluster infrastructure required to serve 2.8 trillion parameters.
88.2% on SWE-bench Pro V2 HARD
Price, access, and privacy
Claude Opus 5.5Kimi K3
Cost
Pro is $20/month ($17/month billed annually); API is $4 per million input tokens and $20 per million output tokens.
Free to download weights; hosted Kimi app is free with usage limits or available via API.
Free tier
Not on the free plan. Free Claude includes Haiku and Sonnet, not Opus.
Yes, available for free with standard rate limits in the Kimi web and mobile apps.
Where to get it
Apps
- Claude, Pro ($20/month)
- Perplexity, Max ($200/month)
- Cursor, Premium ($30/month)
- GitHub Copilot, Copilot Pro ($10/month)
- Claude Code, Pro ($20/month)
- Perplexity, Pro ($20/month)
- Cursor, Premium ($30/month)
- GitHub Copilot, Copilot Pro ($10/month)
- Hugging Face, Free (Free)
- Ollama, Pro ($20/month)
Trains on chats
Anthropic says Free, Pro, and Max chats are used for training only if you allow it, and you choose at signup. The toggle has been reported as on by default, so check it. Settings, then Privacy. Turn off Help improve Claude.
Yes. The Kimi consumer policy says prompts and files can be used to improve models. Ask Kimi support to stop training use if the app has no toggle.
Try both with the same prompt
Claude Opus 5.5
Find the bug in this function, explain the cause, and give the fixed version.
Kimi K3
Refactor this module for clarity and add tests for the edge cases.
Want a sharper prompt? Build one for either model.
Ranking history
- Nov 12, 2026. Claude Fable 5.2 overtook Claude Opus 5.5. Humanity's Last Exam 74.3%.
- Nov 8, 2026. Gemini 4 Argon overtook Claude Opus 5.5. LMArena Creative Writing 1525
- Oct 24, 2026. Ranking method updated. Claude Opus 5.5 leads on the new signal. Writing now ranks on LMArena Creative Writing instead of the general text board. Claude Opus 5.5 leads that board (1520).
- Oct 23, 2026. Claude Opus 5.5 is the first leader on record. LMArena Code 1813; #1 SWE-bench Pro (89.9%)
- Oct 23, 2026. Claude Opus 5.5 is the first leader on record. Humanity's Last Exam 61.4%.
Questions
Is Claude Opus 5.5 or Kimi K3 better for coding & software?
Claude Opus 5.5 ranks ahead for coding & software on LMArena Code. Claude Opus 5.5 is the #1 pick (1813); Kimi K3 is the open weights pick.
Is Claude Opus 5.5 or Kimi K3 better for legal & long documents?
Kimi K3 ranks ahead for legal & long documents on Vals LegalBench. Claude Opus 5.5 is not in today's top three; Kimi K3 is the open weights pick (86.2).
Is Claude Opus 5.5 or Kimi K3 better for writing & marketing?
Claude Opus 5.5 ranks ahead for writing & marketing on LMArena Creative Writing. Claude Opus 5.5 is the alternative pick (1517); Kimi K3 is not in today's top three.
Which is cheaper, Claude Opus 5.5 or Kimi K3?
Claude Opus 5.5: Pro is $20/month ($17/month billed annually); API is $4 per million input tokens and $20 per million output tokens. Kimi K3: Free to download weights; hosted Kimi app is free with usage limits or available via API.
Can I use Claude Opus 5.5 or Kimi K3 for free?
Claude Opus 5.5: Not on the free plan. Free Claude includes Haiku and Sonnet, not Opus. Kimi K3: Yes, available for free with standard rate limits in the Kimi web and mobile apps.
Which is more private, Claude Opus 5.5 or Kimi K3?
Claude Opus 5.5 (Anthropic): Anthropic says Free, Pro, and Max chats are used for training only if you allow it, and you choose at signup. The toggle has been reported as on by default, so check it. Kimi K3 (Moonshot AI): Yes. The Kimi consumer policy says prompts and files can be used to improve models.