Standard Compute
Model comparison 2026

Claude Opus 5.5 vs DeepSeek V4.1 Flash

Claude Opus 5.5
Anthropic · Frontier · Proprietary
$8.80/1M · 1M ctx
DeepSeek V4.1 Flash
DeepSeek · Budget · Open weights
$0.22/1M · 1.0M ctx

Community vote

Pick a winner in each dimension. You can change your vote any time.

Output Quality
Correctness and depth of what it produces
Agentic Ability
Tool calls, instruction-following, and multi-step tasks
Speed
Tokens per second and time-to-first-token
Value for money
How much capability you get per dollar
Reliability
Consistent results: fewer refusals, loops and format breaks

Specs and pricing side by side

Spec
Opus 5.5
DeepSeek V4.1 Flash
Maker
Anthropic
DeepSeek
Blended price / 1M
$8.80
$0.22
Input / output
$4.00 in · $20 out / 1M tokens
$0.04 in · $0.63 out / 1M tokens
Context window
1M
1.0M
Open weights
No
Yes
Tool use
Yes
Yes
Reasoning
Yes
Yes
Output Quality
10.0
8.8
Agentic Ability
10.0
8.8
Speed
7.6
9.4
Value for money
7.4
10.0
Reliability
9.5
8.8

Pricing and capabilities synced from the OpenRouter catalogue. Scores are editorial (0–10).

Verdict: Opus 5.5 or DeepSeek V4.1 Flash?

Updated 2026-10-13

Choose Claude Opus 5.5 if you want the hardest coding and agent work, as the default flagship instead of Fable. Choose DeepSeek V4.1 Flash if you want cheap, high-volume open-weight agent work.

In our editorial scoring, Claude Opus 5.5 leads in 3 of five dimensions (output quality, agentic ability and reliability), while DeepSeek V4.1 Flash leads in 2. On price, Claude Opus 5.5 runs about $8.80 per 1M tokens (blended) and is proprietary; DeepSeek V4.1 Flash is about $0.22 and open-weight.

Where Opus 5.5 falls short
  • Twice Sonnet 5.5's price per token for a small measured gain
  • Released September 2026, so its long-run track record is still short
Full Opus 5.5 breakdown →
Where DeepSeek V4.1 Flash falls short
  • Well below the frontier on long agentic tasks
  • DeepSeek API prices differ between peak and off-peak hours
Full DeepSeek V4.1 Flash breakdown →

The agent matters as much as the model. Compare AI agents →

Every model on this page is included with Standard Compute

Standard Compute

Current frontier models Claude Opus 5.5 · Claude Sonnet 5.5

Your agents never stop.
Your bill never grows.

Frontier models when it counts. Efficient models when it doesn’t. The most intelligence per dollar. One flat bill.

Plans from $19/mo · cancel anytime · 7-day fair refund

7-day fair refund No credit card needed Billing by Stripe1,800+ agent users

Related comparisons