Home / Compare / Claude Opus 5.5 vs DeepSeek V4 Flash Claude Opus 5.5 vs DeepSeek V4 Flash Claude Opus 5.5 grades higher overall (99.5 against 72.1). DeepSeek V4 Flash costs 99% less for the same work.
Model AClaude Fable 5 Claude Haiku 4.5 Claude Opus 4.7 Claude Opus 4.8 Claude Opus 5 Claude Opus 5.5 Claude Sonnet 4.6 Claude Sonnet 5 Claude Sonnet 5.5 DeepSeek R1 0528 DeepSeek V3 DeepSeek V3.1 DeepSeek V3.2 DeepSeek V4 Flash DeepSeek V4 Flash 0731 DeepSeek V4 Pro 0813 DeepSeek V4.1 Flash Gemini 2.5 Flash Gemini 2.5 Pro Gemini 3.1 Flash Lite Gemini 3.1 Pro Gemini 3.5 Flash Gemini 3.7 Flash Gemma 3 12B IT Gemma 3 27B IT Gemma 3 4B IT Gemma 4 26B A4B IT Gemma 4 31B IT GLM 4.6 GLM 4.7 GLM 5.2 GLM 5.3 GLM 5.3 Flash GPT OSS 120B GPT OSS 20B Granite 4.2 8B Hy4 Preview Inkling Small Kimi K2.6 Kimi K3 Ling 3.1 Flash Llama 3.3 70B Instruct Turbo Llama 4 Scout 17B 16E Instruct Meta Llama 3.1 70B Instruct Turbo Meta Llama 3.1 8B Instruct Turbo MiMo V2.6 Flash MiMo V2.6 Pro MiniMax M3 Mistral Small 24B Instruct 2501 Mistral Small 3.2 24B Instruct 2506 Muse Glimmer 30B NVIDIA Nemotron 3 Super 120B A12B NVIDIA Nemotron 3 Ultra 550B A55B NVIDIA Nemotron 3.5 Lightning Phi 4 Qwen2.5 72B Instruct Qwen3 235B A22B Instruct 2507 Qwen3 30B A3B Qwen3 32B Qwen3 Coder 480B A35B Instruct Turbo Qwen3 Next 80B A3B Instruct Qwen3 VL 235B A22B Instruct Qwen3.5 27B Qwen3.5 35B A3B Qwen3.5 397B A17B Qwen3.5 9B Qwen3.6 27B Qwen3.6 35B A3B Qwen3.7 Max Qwen3.8 27B Qwen3.8 Flash Qwen3.8 Max Seed 2.0 Pro Step 5 Preview Claude Opus 5.5
by Anthropic · #1 of 67 overall
Coming soon · price at launch
Context 1M
Input / 1M $4.00
Output / 1M $20.00 Model BClaude Fable 5 Claude Haiku 4.5 Claude Opus 4.7 Claude Opus 4.8 Claude Opus 5 Claude Opus 5.5 Claude Sonnet 4.6 Claude Sonnet 5 Claude Sonnet 5.5 DeepSeek R1 0528 DeepSeek V3 DeepSeek V3.1 DeepSeek V3.2 DeepSeek V4 Flash DeepSeek V4 Flash 0731 DeepSeek V4 Pro 0813 DeepSeek V4.1 Flash Gemini 2.5 Flash Gemini 2.5 Pro Gemini 3.1 Flash Lite Gemini 3.1 Pro Gemini 3.5 Flash Gemini 3.7 Flash Gemma 3 12B IT Gemma 3 27B IT Gemma 3 4B IT Gemma 4 26B A4B IT Gemma 4 31B IT GLM 4.6 GLM 4.7 GLM 5.2 GLM 5.3 GLM 5.3 Flash GPT OSS 120B GPT OSS 20B Granite 4.2 8B Hy4 Preview Inkling Small Kimi K2.6 Kimi K3 Ling 3.1 Flash Llama 3.3 70B Instruct Turbo Llama 4 Scout 17B 16E Instruct Meta Llama 3.1 70B Instruct Turbo Meta Llama 3.1 8B Instruct Turbo MiMo V2.6 Flash MiMo V2.6 Pro MiniMax M3 Mistral Small 24B Instruct 2501 Mistral Small 3.2 24B Instruct 2506 Muse Glimmer 30B NVIDIA Nemotron 3 Super 120B A12B NVIDIA Nemotron 3 Ultra 550B A55B NVIDIA Nemotron 3.5 Lightning Phi 4 Qwen2.5 72B Instruct Qwen3 235B A22B Instruct 2507 Qwen3 30B A3B Qwen3 32B Qwen3 Coder 480B A35B Instruct Turbo Qwen3 Next 80B A3B Instruct Qwen3 VL 235B A22B Instruct Qwen3.5 27B Qwen3.5 35B A3B Qwen3.5 397B A17B Qwen3.5 9B Qwen3.6 27B Qwen3.6 35B A3B Qwen3.7 Max Qwen3.8 27B Qwen3.8 Flash Qwen3.8 Max Seed 2.0 Pro Step 5 Preview DeepSeek V4 Flash
by DeepSeek · #27 of 67 overall
Coming soon · price at launch
Context 1M
Input / 1M $0.090
Output / 1M $0.18 Better overall
Claude Opus 5.5
Grade 99.5 vs 72.1
Cheaper
DeepSeek V4 Flash
99% less, $0.11 vs $8.00 blended
Larger context
DeepSeek V4 Flash
1M vs 1M tokens
SWE-Bench Pro
Claude Opus 5.5
89.9% vs 52.6%
Head to head Public benchmarks. Longer is better; each value links to its source.
LMArena Text Elo-style rating · LMArena (CC BY 4.0) · Oct 15, 2026 Claude Opus 5.5 Claude Opus 5.5: —
SWE-Bench Pro % of tasks resolved · Scale AI SWE-Bench Pro · Sep 22, 2026 · reference DeepSeek V4 Flash DeepSeek V4 Flash: —
Claude Opus 5.5 Claude Opus 5.5: —
LiveCodeBench pass@1, % · LiveCodeBench · Apr 22, 2026 · reference Claude Opus 5.5 Claude Opus 5.5: —
Claude Opus 5.5 $1,600 /month
DeepSeek V4 Flash $25.20 /month
DeepSeek V4 Flash saves you $1,575 a month at this usage, $18,898 a year.
At a glance Attribute Claude Opus 5.5 DeepSeek V4 Flash Made by Anthropic DeepSeek Availability Coming soon Coming soon Overall grade Excellent · 99.5 Excellent · 72.1 Overall rank #1 of 67 #27 of 67 Input price $4.00 per 1M $0.090 per 1M Output price $20.00 per 1M $0.18 per 1M Context window 1,000,000 tokens 1,048,576 tokens Reasoning levels Yes No Reads images Yes No Model ID claude-opus-5-5 deepseek-v4-flash
Try both with one key Same endpoint, same key, both hosted in the USA. Change one word to switch models, in Claude Code, Cursor, Cline or your own code.
Get your API key # Ask either model the same thing
curl https://fullsendai.com/v1/chat/completions \
-H "Authorization: Bearer $FULLSEND_API_KEY " \
-d '{"model": "claude-opus-5-5", "messages": [...]}'
# …then swap one word
-d '{"model": "deepseek-v4-flash", "messages": [...]}' Questions Is Claude Opus 5.5 or DeepSeek V4 Flash better? Claude Opus 5.5 grades 99.5 against 72.1 for DeepSeek V4 Flash, from public benchmarks.
Which is cheaper, Claude Opus 5.5 or DeepSeek V4 Flash? DeepSeek V4 Flash: $0.090 in and $0.18 out per million tokens, against $4.00 and $20.00 through FullsendAI.
Which has the larger context window? DeepSeek V4 Flash, with 1,048,576 tokens.
Can I use both with one API key? Yes, once they launch: both are coming soon, at the prices shown, and both will use the same FullsendAI key.
Scores: LMArena (CC BY 4.0), SWE-bench, Scale AI SWE-Bench Pro, Terminal-Bench, LiveCodeBench, and model makers’ published results where marked v. Prices are FullsendAI’s, per million tokens. Data as of Oct 28, 2026.
