Claude Opus 5.5

Text & chatNewAvailable
by AnthropicModel ID: claude-opus-5-5

Anthropic's current Opus model for long-running agentic coding and knowledge work. 1M-token context window, up to 128K output tokens, adaptive thinking that is always on.

Price ยท 1M in / out
US$4.80 / US$24.00
Context
1.000.000 tokens
Max. output
128.000 tokens
Input โ†’ output
Text + Image โ†’ Text
Developer
Anthropic
Updated
September 23, 2026
01

Playground

Try Claude Opus 5.5

Chat

US$4.80/1M in
Try Claude Opus 5.5

Send a message. The answer arrives in full once the model is done (no streaming).

System prompt
Max. answer length (tokens)

This run

at most US$0.0246 ยท 2.46 credits reserved

Billed by the tokens actually used; the unused part of the reservation is refunded.

For accounts without a purchase: runs above 2 credits need a top-up.

New here?

5 free credits (US$0.05) when you sign up with Google

Usable 24 hours after sign-up, up to 5 runs per day and at most 2 credits per run. Other sign-in methods start without credits.

02

About Claude Opus 5.5

TL;DRAs of September 23, 2026

Claude Opus 5.5 is a model by Anthropic in the Text & chat category. On Railwail, Claude Opus 5.5 costs US$4.80 per 1M input tokens and US$24.00 per 1M output tokens. The context window holds 1.000.000 tokens, and one response can be up to 128.000 tokens long.

Claude Opus 5.5 is the newest model in Anthropic's Opus line and the model Anthropic recommends as the starting point for most workloads. It accepts text and image input and returns text, with a 1M-token context window and up to 128K output tokens per request. Thinking is always on and adaptive: the model decides how much to reason, steered by the effort setting, whose default is medium. Sampling parameters such as temperature are not accepted. Reliable knowledge cutoff: June 2026.
03

Pricing

Prices in US dollars. Usage is charged from prepaid credits.
InputUS$4.80 / 1M tokens
OutputUS$24.00 / 1M tokens
  • Billed by the tokens each request actually uses.
  • 1 credit = US$0.01

Cost calculator

Price calculator

/ req.
/ req.

Total

US$1.68

168 credits

Per request

US$0.0168 ยท 1.68 credits

Each request is rounded up to 0.01 credits.

04

API

Call Claude Opus 5.5 with your Railwail API key. Use this model ID in the request:
curl https://railwail.com/api/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-5-5",
    "messages": [
      {
        "role": "user",
        "content": "Explain what a vector database is in two sentences."
      }
    ],
    "max_tokens": 1024
  }'
Set your key as RAILWAIL_API_KEYCreate API key
05

Specifications

Model ID
claude-opus-5-5
Developer
Anthropic
Category
Text & chat
Input
Text, Image
Output
Text
Context window
1.000.000 tokens
Max. output
128.000 tokens
Billing
By usage (tokens or GPU time)
Released
September 22, 2026
Lifecycle
Current version
Catalog entry updated
September 23, 2026

Input parameters

Inputs and settings from the model's input schema. The example in the API section shows which of them the API accepts.

  • promptrequired

    User message

    Type: Text
    Default: โ€“
    Allowed values: up to 32.000 characters
  • stream
    Type: Yes/no
    Default: false
    Allowed values: โ€“
  • max_tokens
    Type: Integer
    Default: 4096
    Allowed values: 1 to 128.000
  • system_prompt

    Optional system instruction

    Type: Text
    Default: โ€“
    Allowed values: up to 8.000 characters

Tags

  • anthropic
  • claude
  • opus
  • flagship
  • agentic
  • coding
  • vision
  • long-context
  • 1m-context
06

Use cases

07

Frequently asked questions

What is Claude Opus 5.5?

Claude Opus 5.5 is a model by Anthropic in the Text & chat category. On Railwail you can call it with an API key through the Railwail API.

How much does Claude Opus 5.5 cost on Railwail?

On Railwail, Claude Opus 5.5 costs US$4.80 per 1M input tokens and US$24.00 per 1M output tokens. You are charged for what each request actually uses. Usage is paid from prepaid credits; 1 credit equals US$0.01.

What is the context window of Claude Opus 5.5?

The context window of Claude Opus 5.5 holds 1.000.000 tokens. One response can be up to 128.000 tokens long.

How fast is Claude Opus 5.5?

There are not enough measured runs of Claude Opus 5.5 on Railwail yet to state a run time. It depends on the input, the settings and the load at the provider.

Is Claude Opus 5.5 better than Claude Fable 5.1?

That depends on the task. Claude Opus 5.5 (Anthropic) and Claude Fable 5.1 (Anthropic) are both models in the Text & chat category. The comparison page shows their prices and specifications side by side.

Compare Claude Opus 5.5 and Claude Fable 5.1

Can Claude Opus 5.5 process images?

Yes. Claude Opus 5.5 accepts images as input in addition to text.

How do I use Claude Opus 5.5 through the API?

Create a Railwail API key and send your request with the model ID claude-opus-5-5. Code examples for curl, Python and JavaScript are in the API section of this page.

08

Comparable models

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Use Claude Opus 5.5 via the API

One API key for every model on Railwail. Usage is charged from prepaid credits, 1 credit = US$0.01.