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Model comparisons

Claude Opus 5.5 vs DeepSeek V4.1 Flash

DeepSeek V4.1 Flash bills 93% less than Claude Opus 5.5 per million output tokens. Tier prices, request fields and limits side by side.

Claude Opus 5.5

Claude Opus 5.5 chat from Anthropic, released 22 September 2026, through an OpenAI-compatible endpoint. It takes up to 1,000,000 tokens and returns up to 128,000, always thinks, offers low, medium or high effort and up to 128 tool definitions.

View model details →View sample outputs →

DeepSeek V4.1 Flash

DeepSeek V4.1 Flash chat through an OpenAI-compatible endpoint. It takes up to 1,048,576 tokens of text and image context and returns up to 384,000, with low or high reasoning effort, up to 128 tool definitions and JSON format.

View model details →View sample outputs →

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The short answer

Start with the input you have, the result you want and your budget. These are the differences that affect that choice.

  • DeepSeek V4.1 Flash costs 93% less per million output tokens. Compare the input and cache rates below for longer conversations.
  • Both are listed as Uncensored. Compare the examples and content-test details on each model page for the scenes you want to create.

Compare the published examples, then try the same input on both models with matching settings.

Test scores side by side

The Spicy Index and Freedom Score for both models, from the same daily calculation as the leaderboards.

Test scores side by side
MeasureClaude Opus 5.5DeepSeek V4.1 Flash
Spicy Index82.581.9
Freedom Score88.990.4
EvidenceTested 5 of 5 probe types · 24 runsTested 5 of 5 probe types · 31 runs
Range if the rest pass88.9–88.990.4–90.4
Price$7.20 per 1M mixed tokens (3 input : 1 output)$0.525 per 1M mixed tokens (3 input : 1 output)
ReviewsRead the Claude Opus 5.5 reviewRead the DeepSeek V4.1 Flash review
See both on the leaderboard →

Current price

Price at the same setting

A start price answers a different question than the one you have. These are the tiers both models publish, matched setting for setting, in US dollars per billed unit with no conversion step in between.

Swipe horizontally to compare all fields.

Price at the same setting
TierClaude Opus 5.5DeepSeek V4.1 FlashDifference
Input$3.6 / 1 million tokens$0.3 / 1 million tokensDeepSeek V4.1 Flash −91%
Cached input$0.18 / 1 million tokens$0.006 / 1 million tokensDeepSeek V4.1 Flash −96%
Output$18 / 1 million tokens$1.2 / 1 million tokensDeepSeek V4.1 Flash −93%

What one ordinary job costs

  • Claude Opus 5.5: $7.2 for one million input and two hundred thousand output tokens.
  • DeepSeek V4.1 Flash: $0.54 for one million input and two hundred thousand output tokens.

Arithmetic on the published rates at each model's own default setting, not a quote. The console prices your actual settings before a request is accepted.

About this comparison

Controls and limits

Every row here is read from the JSON Schema the endpoint validates against, so it matches what the API will really accept rather than a feature list written by hand.

Swipe horizontally to compare all fields.

Claude Opus 5.5 vs DeepSeek V4.1 Flash
Controls and limitsClaude Opus 5.5DeepSeek V4.1 Flash
Supported taskschatchat
Input context1,000,000 tokens1,048,576 tokens
Maximum output128,000 tokens384,000 tokens
Tool callingYesYes
ExecutionSynchronous, with streamingSynchronous, with streaming
Request timeout60 minutes60 minutes
AvailabilityLiveLive

Do low-filter models allow every request?

Content policy, side by side

Two separate facts sit behind these labels. The first is what we do, which is nothing: no platform content filter, and no maturity flag to set on a request. The second is what each model does on its own, and that is the only part that varies between these two.

Claude Opus 5.5

Uncensored

We add no content filter to this model, but like most chat models it declines a blunt request that comes with no context. It writes unrestricted fiction reliably once your system prompt sets up a fiction-writing context, or once the request is framed as a story. Legal and consent duties remain with the customer.

DeepSeek V4.1 Flash

Uncensored

We add no content filter to this model, but like most chat models it declines a blunt request that comes with no context. It writes unrestricted fiction reliably once your system prompt sets up a fiction-writing context, or once the request is framed as a story. Legal and consent duties remain with the customer.

Usage note Submit only material you are authorized to handle. Do not use it to invade privacy, impersonate a real person, or create sexual content involving minors.

Use these content labels to shortlist models, then open each model page for available examples and content-test details.

The label never changes your obligations. Age, consent, real-person likeness and the law where you operate stay with you, and SpicyAPI does not inspect each request.

Can I swap the model ID without changing the request body?

Request body, field by field

The task lifecycle is shared; the body is not. Each endpoint publishes its own JSON Schema and the API validates against that, so this is the list to reconcile before a switch.

  • 6 fields appear in both request bodies under the same names. stop, tools, messages, max_tokens, tool_choice, reasoning_effort
  • Only Claude Opus 5.5 accepts: parallel_tool_calls.
  • Only DeepSeek V4.1 Flash accepts: response_format.
  • Claude Opus 5.5 requires messages.
  • DeepSeek V4.1 Flash requires messages.
  • Both reject unknown fields outright, so a parameter left over from the other model comes back as a validation error instead of being quietly ignored.

How to choose

How to choose

Maximum output

DeepSeek V4.1 Flash can return more in one reply: up to 384,000 tokens against the other model's ceiling.

Input context

DeepSeek V4.1 Flash takes the longer prompt: up to 1,048,576 input tokens in a single request.

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Moving from one to the other

The model identifiers are anthropic/claude-opus-5.5/chat and deepseek/v4.1-flash/chat, and both go in the same field of the same request.

Both return the response on the chat request. With streaming enabled, read the stream until it finishes; there is no media task to poll.

Both use the same submit-and-track flow, but their required inputs may differ. Check each model page before switching.

One key, one balance, one set of spend caps. Both bill to the same account in US dollars, and the per-key daily, monthly and lifetime limits apply to whichever one you call.

Questions developers ask

Which is cheaper, Claude Opus 5.5 or DeepSeek V4.1 Flash?

Which is cheaper, Claude Opus 5.5 or DeepSeek V4.1 Flash?

DeepSeek V4.1 Flash costs 93% less per million output tokens. Compare the input and cache rates below for longer conversations. Prices may change; check the estimate shown for your actual settings before submitting.

How long can a single request run?

Claude Opus 5.5 allows 60 minutes per task and DeepSeek V4.1 Flash allows 60. Those are ceilings rather than typical times — most requests finish far sooner — but they are what your own client timeout has to survive.