// Claude model comparison

Claude Opus 5.5vsClaude Sonnet 5.5

Q: Can I use both through GPTProto?

Yes. The catalog includes [Claude Opus 5.5](/model/claude/claude-opus-5-5) and [Claude Sonnet 5.5](/model/claude/claude-sonnet-5-5) model pages with current pricing, API examples, and a Playground. The [Claude catalog](/model/claude) shows the currently available lineup.

By GPTProtoUpdated October 14, 2026

Claude Opus 5.5 and Claude Sonnet 5.5 share a 1-million-token context window, a standard 128,000-token output limit, and text-and-image input. The difference is where they earn their keep: Anthropic positions Opus for long-running agentic coding and complex knowledge work, while Sonnet is the faster, lower-cost fit for well-scoped daily tasks, bug fixes, and polished documents.

The short answer: start with Sonnet 5.5 when speed and cost per call matter and the task has a clear finish line. Use Opus 5.5 when the work stays open-ended across a codebase, multiple tool calls, or decisions that require sustained judgment. Compare cost per successful task—not just the token rate—before standardizing on either model.

Explore Claude Opus 5.5 on GPTProto Explore Claude Sonnet 5.5 on GPTProto

Claude Opus 5.5↗Anthropic · claude-opus-5-5

Best forBest for long-running coding agents, multi-step code changes, and complex knowledge work.

Per 1M tokens · base list tier

Input~~$4.00~~$3.60/M−10%

Output~~$20.00~~$18.00/M−10%

View model page

Claude Sonnet 5.5↗Anthropic · claude-sonnet-5-5

Best forBest for everyday coding, focused bug fixes, document work, and agent steps where a faster response and lower token cost matter.

Per 1M tokens · base list tier

Input~~$2.00~~$1.80/M−10%

Output~~$10.00~~$9.00/M−10%

View model page

// Side by side

Opus 5.5 vs Sonnet 5.5At a Glance.

These are the differences that matter for an API decision. GPTProto prices are the catalog rates checked on October 13, 2026; check the live pages before estimating a production bill. Standard token prices do not include cache or other feature-specific charges.

Spec

Claude Opus 5.5

Claude Sonnet 5.5

Provider

Anthropic

Model ID

claude-opus-5-5

claude-sonnet-5-5

Availability

99.7%

Last 7 days

97.7%

Last 7 days

Release date

September 22, 2026

September 28, 2026

Input

$3.60~~$4.00~~ official list

$1.80~~$2.00~~ official list

Output

$18.00~~$20.00~~ official list

$9.00~~$10.00~~ official list

You save

−10%vs Anthropic list price

Cache read

$0.18~~$0.20~~ official list

Cache write

$4.50~~$5.00~~ official list

$2.25~~$2.50~~ official list

Caching

Supported

Latency (p50)

3.38 s

1.91 s

Throughput (p50)

71 tok/s

100 tok/s

Comparative latency

Moderate

Fast

Context window

1M tokens

Max output tokens

128K tokens

Thinking

Adaptive thinking is always on, with adjustable effort

Adaptive thinking; adjustable effort

Accepts

TEXTIMAGE

Returns

TEXT

Built-in capabilities

Web SearchFile Analysis

Tool use

Supported

Stream cancellation

Supported

No prompt training

YesGPTProto Privacy Policy §5.2

Where it earns its keep

Long-running agentic coding, difficult code review, and complex knowledge work

Well-scoped coding, bug fixes, polished documents, and everyday knowledge work

Best first test

Long-running agentic coding and complex knowledge work

Well-scoped coding, bug fixes, and everyday knowledge work

In the catalog since

Sep 2026

API usage

curl https://gptproto.com/v1/chat/completions \
  -H "Authorization: Bearer $GPTPROTO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-5-5",
    "messages": [{"role": "user", "content": "Hi"}]
  }'

curl https://gptproto.com/v1/chat/completions \
  -H "Authorization: Bearer $GPTPROTO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5-5",
    "messages": [{"role": "user", "content": "Hi"}]
  }'

Prices per 1M tokens. Official list rates from Anthropic via the GPTProto catalog (raw price / 740). GPTProto rates apply price_multiplication 0.9. Latency and benchmarks are OpenRouter figures as of 2026-10-14.

Input & output price · per 1M tokens · each pair scaled to its official rate

OfficialGPTProto

Claude Opus 5.5Anthropic

Input$4.00

Input−10%$3.60

Output$20.00

Output−10%$18.00

Claude Sonnet 5.5Anthropic

Input$2.00

Input−10%$1.80

Output$10.00

Output−10%$9.00

// Price comparison

The 2× Token-Price Gapand When It Matters.

On GPTProto, Sonnet 5.5 costs half as much as Opus 5.5 per input and output token: $1.80/$9 versus $3.60/$18 per million tokens at the current displayed rates. Both models support a 1M-token context window. Cache and feature-specific charges can change the full bill.

For a request with 10,000 uncached input tokens and 1,000 output tokens, the listed GPTProto token rates imply about $0.027 for Sonnet 5.5 or $0.054 for Opus 5.5. This is an illustration of input and output token charges only. Prompt caching, tool calls, retries, and other usage can change the final bill. If Opus completes a difficult task that Sonnet requires several attempts to solve, the cheaper token rate may not produce the cheaper successful result.

Check the live Sonnet 5.5 rate and Opus 5.5 rate before choosing a production default.

// Savings calculator

Run Your Own Numbers.Not Ours.

Multiply your expected monthly input and output tokens by the corresponding rates displayed on GPTProto to estimate base token costs for each model. Then test a representative set of real tasks. A useful budget includes cache reads and writes, retries, tool usage, and the share of requests each model completes successfully.

Pricing model

Input tokens per month (millions)

M tokens

Output tokens per month (millions)

M tokens

You keep, per year

$1,080

Monthly run rateOfficialGPTProtoSave

Input$400$360$40

Output$500$450$50

Per year$10,800$9,720$1,080

Excludes top-up bonus credits. Assumes flat usage at the published per-1M-token rate — cache, tools, and retries are extra.

See top-up tiers

// Speed, uptime & access

How Fast. How Reliable.What It Takes To Call It.

Anthropic labels Sonnet 5.5 Fast and Opus 5.5 Moderate in its model overview. Those labels describe relative model latency, not the end-to-end time of your application. Prompt length, reasoning effort, tools, response size, and live service conditions all affect a real request.

Spec

Claude Opus 5.5

Claude Sonnet 5.5

Latency (p50)

3.38 s

1.91 s

Throughput (p50)

71 tok/s

100 tok/s

Providers serving it

Usage (last 30 days)

—

Reasoning

Always onCannot be disabled; effort is adjustable

Always onEffort is adjustable; OpenRouter lists reasoning as mandatory

Effort levels

LOWMEDIUMHIGHXHIGHMAX

Default effort

High

Supported parameters

reasoningmax_tokensstoptool_choicetoolsresponse_format

OpenRouter figures as of 2026-10-14. “Fast” and “Moderate” are Anthropic’s relative classifications. Not a GPTProto SLA.

// Top-up

Pay Per Token.
One Balance for Both Models.

Use one GPTProto balance to test both Claude models at their displayed rates. You can test Sonnet for routine calls and reserve Opus for the cases that need it without setting up a second model provider inside your application.

$15

Straight credit · no bonus

Get started. Great for testing the endpoint and trying new models.

What They Can Do.What Benchmarks Cannot Decide.

Anthropic describes Sonnet 5.5 as a faster complement to Opus 5.5 for focused work, including bug fixes and polished documents, slides, and spreadsheets. At high reasoning effort, Sonnet can approach Opus on some published evaluations. Opus remains the candidate for complex, open-ended work that needs sustained judgment. That is a task distinction, not a claim that either model wins every benchmark.

Spec

Claude Opus 5.5

Claude Sonnet 5.5

Intelligence Index

57.6

Vals Index

67.0%

Code Migration

66.6%

69.8%

IOI

95.1%

83.1%

ProgramBench

18.5%

6.5%

Design Arena · Website

1335 Elo#4 in category

1332 Elo#5 in category

Design Arena · UI components

1384 Elo#2 in category

1379 Elo#3 in category

Design Arena · Game dev

1461 Elo#1 in category

1456 Elo#2 in category

Artificial Analysis, Vals AI, and Design Arena figures as listed on OpenRouter, 2026-10-14.

// Verdict

Which Model FitsYour Workload?

Start with the model whose finish line you can already describe.

Claude Opus 5.5claude-opus-5-5

Choose Opus 5.5 for sustained judgment

Use Opus 5.5 when an agent must inspect a large codebase, plan and execute a multi-step change, reason across many documents, or review a difficult result.
Its higher per-token price is easier to justify when a failed or repeated run costs more than the difference between model rates.
Anthropic classifies its comparative latency as Moderate. Measure your own prompt, tools, and effort setting.

Test Claude Opus 5.5 on GPTProto

Claude Sonnet 5.5claude-sonnet-5-5

Choose Sonnet 5.5 for well-scoped work

Use Sonnet 5.5 for repeatable coding tasks, localized bug fixes, document drafting, structured analysis, and agent steps that have clear success criteria.
The lower listed token price and Fast relative latency make it a sensible first candidate for frequent calls.
Check result quality and retry rate before treating the lower token price as a lower cost per completed task.

Test Claude Sonnet 5.5 on GPTProto

Use both in one workflow

A practical routing pattern is to send routine, well-scoped steps to Sonnet and escalate ambiguous or high-stakes steps to Opus. Keep the same evaluation criteria at each handoff and record when escalation actually improves the final result. GPTProto’s Claude catalog gives you both model pages in one place.

// Context & multimodal

Context, Output,and Multimodal Support.

Anthropic specifies a 1M-token context window and a standard 128K-token output limit for both models. The output budget includes thinking tokens, not just the visible answer. They accept text and image input and return text; check the supported request limits for your GPTProto route. Matching limits do not guarantee matching performance on a long codebase or document: test evidence retrieval, instruction following, and accuracy at the prompt lengths you expect to use.

Both support adaptive thinking. Opus 5.5 keeps it on, with adjustable effort; Sonnet 5.5 supports adaptive thinking and adjustable effort. OpenRouter lists reasoning as mandatory for both. Reasoning settings can change latency, token usage, and results, so compare the models using settings that match your application. For document-heavy tasks, GPTProto also has model-specific Sonnet file-analysis and Opus file-analysis pages.

// How to decide

How to Make a FairOpus 5.5 vs Sonnet 5.5 Decision.

Build an evaluation set from actual production tasks: straightforward cases, long-context cases, and the failures that matter most. Run both models with equivalent instructions, input, tools, and grading rules. Compare task success, total tokens, retries, and end-to-end time. Report the cost per successful task alongside the per-token rate. Use a separate set for complex cases; a single average can hide where Opus earns its higher price or where Sonnet is sufficient.

// Get started

Test Opus 5.5 and Sonnet 5.5on GPTProto.

Both model pages include current pricing, API examples, and a Playground. Review the live rate, run your own prompts, and choose the model—or routing rule—that meets your quality, speed, and budget requirements. Explore the Claude model catalog.

View Claude Opus 5.5 API and pricing View Claude Sonnet 5.5 API and pricing

// FAQ

Opus 5.5 vs Sonnet 5.5.Straight Answers.

01Is Claude Sonnet 5.5 cheaper than Claude Opus 5.5?+

Yes. Displayed input/output rates are $1.80/$9 for Sonnet 5.5 and $3.60/$18 for Opus 5.5 per million tokens. Caching and other charges can affect a complete workload bill; check each model’s live GPTProto page for the current rate.

02Which model is better for coding?+

Sonnet 5.5 is a strong first choice for focused bug fixes and everyday coding. Opus 5.5 is designed for longer, more complex agentic coding work that needs sustained judgment across a codebase. Test both on your own tasks and compare correct completions, retries, latency, and total cost.

03Are the context and output limits different?+

No. Anthropic lists a 1M-token context window and a standard 128K-token maximum output for both Claude Opus 5.5 and Claude Sonnet 5.5. Those are limits, not a guarantee of equal quality on very long inputs or a recommendation to generate the maximum output.

04Is Opus 5.5 faster than Sonnet 5.5?+

Anthropic classifies Sonnet 5.5 as Fast and Opus 5.5 as Moderate relative to its other models. Neither label promises a specific latency on GPTProto. On OpenRouter’s provider medians checked October 14, 2026, Sonnet’s p50 latency was 1.91 s and Opus’s was 3.38 s. Measure both with your actual prompt lengths, reasoning settings, and tool calls.

05Do both models support adaptive thinking?+

Yes. Opus 5.5 has adaptive thinking always on, with adjustable effort. Sonnet 5.5 supports adaptive thinking and adjustable effort. OpenRouter lists reasoning as mandatory for both. Test the settings you plan to use because more reasoning can change speed, token usage, and output quality.

06Can I use both through GPTProto?+

Yes. The catalog includes Claude Opus 5.5 and Claude Sonnet 5.5 model pages with current pricing, API examples, and a Playground. The Claude catalog shows the currently available lineup.

// Social proof

See how others use GPTProto.

Creators and developers share the models and workflows they built with.

Blogstra

Reddit · r/Bloggers

#Routing

For a team already juggling DeepSeek, Kimi, Qwen, or other providers, a shared routing layer can be reasonable if it removes duplicated work and the fallback behavior is tested. GPTProto is one implementation of this approach.

X (Twitter) · @ChillaiKalan__

#Cost

I've been testing GPTProto recently, and it's honestly made my creative workflow much simpler. Instead of paying for multiple subscriptions, I can access several leading AI models from one place.

Sanskriti Naruka

X (Twitter) · @snskritinaruka

#Video

I turned this single prompt into a cinematic fantasy video using GPTProto. "Continuous 15-second cinematic shot, 4K resolution, hyper-realistic dark fantasy photorealism…"

Caden Flux

X (Twitter) · @Caden_Flux

#Video

I challenged myself to create a cinematic AI cooking short in just 15 seconds. I used GPTProto to bring the entire workflow together, from image generation to video, all in one place.

Zara

X (Twitter) · @ZaraIrahh

#Creative

Made with Seedance 2.0 + GPT Image 2 on GPTProto. A Pixar-style commercial with the perfect glow.

Many-Operation2625

Reddit · r/LLMDevs

#Integration

What worked for me was pointing the cloud connections at GPTProto so the frontend only sees one endpoint and I just change the model name to swap. I am not rebuilding a connection from scratch every time.

// From the blog

AI Model Guides.Practical API Tutorials.

Compare models, learn API setup, and explore image and video workflows for real projects.

View all posts →

// Get started

Your next 100,000,000 tokensshouldn't cost full price.

Create images and videos online, or bring text, image, and video models into your app with one API key. Explore discounted rates on selected models.

✓OpenAI-compatible
✓200+ models
✓10–30% lower than official
✓High uptime, auto-failover

✓Copied to clipboard

Claude Opus 5.5vsClaude Sonnet 5.5

Opus 5.5 vs Sonnet 5.5At a Glance.

The 2× Token-Price Gapand When It Matters.

Run Your Own Numbers.Not Ours.

How Fast. How Reliable.What It Takes To Call It.

Pay Per Token.One Balance for Both Models.

What They Can Do.What Benchmarks Cannot Decide.

Which Model FitsYour Workload?

Use both in one workflow

Context, Output,and Multimodal Support.

How to Make a FairOpus 5.5 vs Sonnet 5.5 Decision.

Test Opus 5.5 and Sonnet 5.5on GPTProto.

Opus 5.5 vs Sonnet 5.5.Straight Answers.

See how others use GPTProto.

AI Model Guides.Practical API Tutorials.

GLM 5.3 Flash vs Claude Haiku 5.5: Which Is Better for Coding and Agents?

5 Best AI Image Generation APIs for Developers in 2026: 18 Outputs Tested

ChatGPT Free vs Paid: Which Plan Is Actually Worth It in 2026?

Your next 100,000,000 tokensshouldn't cost full price.

Pay Per Token.
One Balance for Both Models.