Claude Sonnet 5.5 API, pricing, playground & code

Name: Claude Sonnet 5.5 API
Brand: Anthropic

Overview

About Claude Sonnet 5.5

The fast Claude 5.5: near-Opus coding and knowledge work, 30%+ faster than Sonnet 5, at half Opus 5.5's price. Every model on CompanyFabric shares the same API key, billing balance, and rate-limit envelope, one integration covers the entire library.

Facts

At a glance

Availability

Live

Pricing

$2/Mtok in

Metered exactly per call

Context window

1,000k tokens

Commercial use

See license

Commercial use of outputs permitted per Anthropic's usage policies.

Variants

All endpoints

Claude Sonnet 4.5

$3/Mtok in

Frontier-quality text and reasoning through one OpenAI-compatible endpoint.

Chat Completions

Claude Haiku 4.5

$1/Mtok in

Fast, cheap frontier-family model for high-volume tasks.

Chat Completions

Claude Opus 4.6

$5/Mtok in

The frontier tier for the hardest reasoning and agentic work.

Chat Completions

Claude Fable 5

$10/Mtok in

Anthropic's first Mythos-class model, the new flagship tier above Opus, tuned for the hardest reasoning and agentic work.

Chat Completions

Claude Opus 5

$5/Mtok in

The Claude 5 generation's deep-work model, maximum-capability reasoning for research, architecture, and hard agentic tasks.

Chat Completions

Claude Opus 5.5

$4/Mtok in

First of the Claude 5.5 generation: Fable-class agentic coding and computer use at 20% below Opus 5.

Chat Completions

Claude Sonnet 5.5

$2/Mtok in

The fast Claude 5.5: near-Opus coding and knowledge work, 30%+ faster than Sonnet 5, at half Opus 5.5's price.

Chat Completions

Claude Fable 5.1

$10/Mtok in

Anthropic's top generally available model, tied for first on the Artificial Analysis Intelligence Index.

Chat Completions

Quickstart

How to use the Claude Sonnet 5.5 API

1
Create a free CompanyFabric account, starter credits are included, no card required.
2
Copy your API key from the dashboard. One key covers every model in the library.
3
Point any OpenAI SDK at api.companyfabric.com/v1 and set model to "anthropic/claude-sonnet-5-5".
4
Read the exact metered cost of the call from the response, the same number shown in the playground.

Use cases

What teams build with it

Agents & copilots

Drive agent loops, tool calls, and user-facing assistants over the OpenAI-compatible endpoint.

agentstool useassistants

Content pipelines

Summarization, rewriting, and structured generation at metered per-token cost.

contentsummarization

Extraction & classification

Turn unstructured input into typed JSON with schema-constrained output.

extractionjson mode

Get better output

Prompting tips

State the output format before the task, models follow contracts declared early.
Few-shot beats description: two worked examples outperform a paragraph of rules.
Cap output length explicitly when cost matters; output tokens dominate most bills.

Exact, metered, prepaid

Claude Sonnet 5.5 pricing

Claude Sonnet 5.5 pricing is per token: $2 / M input · $10 / M output. Output tokens cost 5× input tokens, so long generations, not long prompts, are what actually drive most bills. A typical call with a 2k-token prompt and a 1k-token answer costs about $0.0140.

Every call is metered exactly and attributed to your key, the dashboard, the API usage response, and your invoice all read from the same ledger row. Cap any key's monthly spend with a budget cap, and bring your own provider key (BYOK) at 0% platform fee if you already have a direct contract.

Endpoint	Type	Price
Claude Sonnet 4.5	Chat	$3 / M input · $15 / M output
Claude Haiku 4.5	Chat	$1 / M input · $5 / M output
Claude Opus 4.6	Chat	$5 / M input · $25 / M output
Claude Fable 5	Chat	$10 / M input · $50 / M output
Claude Opus 5	Chat	$5 / M input · $25 / M output
Claude Opus 5.5	Chat	$4 / M input · $20 / M output
Claude Sonnet 5.5	Chat	$2 / M input · $10 / M output
Claude Fable 5.1	Chat	$10 / M input · $50 / M output

Starter credits

Use Claude Sonnet 5.5 free

Your CompanyFabric starter credits cover your first Claude Sonnet 5.5 calls at no cost, create a free account, no card required, and the credits apply to Claude Sonnet 5.5 and every other model on the key. When they run out, prepaid credits or BYOK (0% fee) take over with no plan to pick.

All ways to use AI models free →

Production-grade

Code samples

import OpenAI from "openai"

const client = new OpenAI({
  baseURL: "https://api.companyfabric.com/v1",
  apiKey: process.env.COMPANYFABRIC_API_KEY,
})

const res = await client.chat.completions.create({
  model: "anthropic/claude-sonnet-5-5",
  max_tokens: 1024,
  temperature: 0.7,
  messages: [{ role: "user", content: "Say hello from the fabric." }],
})

console.log(res.choices[0].message.content)

Playground

Try it in the browser

Playground$2 in / $10 out per 1M tokens

Model

Max output

Prompt

Comparisons

Claude Sonnet 5.5 vs the alternatives

Claude Sonnet 5.5 vs GPT-6 Sol

Claude Sonnet 5.5 and GPT-6 Sol compete for the same text workloads. Both run behind the same CompanyFabric key at exact metered prices, A/B them on your real prompts and let the outputs decide, then switch with a one-line change.

Full comparison: Claude Sonnet 5.5 vs GPT-6 Sol →

Claude Sonnet 5.5 vs Gemini 3.1 Pro (preview)

Claude Sonnet 5.5 and Gemini 3.1 Pro (preview) compete for the same text workloads. Both run behind the same CompanyFabric key at exact metered prices, A/B them on your real prompts and let the outputs decide, then switch with a one-line change.

Full comparison: Claude Sonnet 5.5 vs Gemini 3.1 Pro (preview) →

Claude Sonnet 5.5 vs Grok 4.6

Claude Sonnet 5.5 and Grok 4.6 compete for the same text workloads. Both run behind the same CompanyFabric key at exact metered prices, A/B them on your real prompts and let the outputs decide, then switch with a one-line change.

Full comparison: Claude Sonnet 5.5 vs Grok 4.6 →

Compare

Claude Sonnet 5.5 head to head

Claude Sonnet 5.5vsGPT-6 Sol Claude Sonnet 5.5vsGemini 3.1 Pro (preview)Claude Sonnet 5.5vsGrok 4.6

FAQ

Frequently asked questions

How much does the Claude Sonnet 5.5 API cost?

$2 / M input · $10 / M output. Every call is metered exactly and shown before you run it.

How do I get a Claude Sonnet 5.5 API key?

Create a CompanyFabric account, and one key unlocks Claude Sonnet 5.5 and every other model in the library. Free starter credits are included, no subscription, no card required to try it.

Why use Claude Sonnet 5.5 on CompanyFabric instead of going direct?

One key, one prepaid balance, and one rate-limit envelope across the whole library, at pricing at parity with or below the direct API. Model switching is a one-line change, and BYOK routing is 0% fee.

Is the API OpenAI-compatible?

Yes, point any OpenAI SDK at api.companyfabric.com/v1 and set model to "anthropic/claude-sonnet-5-5".

Can I use the output commercially?

Commercial use of outputs permitted per Anthropic's usage policies.

How does billing work?

Prepaid credits via card, or BYOK with your own provider keys at 0% platform fee. No subscription required; balances never expire.

Provider

About Anthropic

Anthropic publishes the claude family. Also in this family: Claude Sonnet 4.5, Claude Haiku 4.5, Claude Opus 4.6, Claude Fable 5, Claude Opus 5, Claude Opus 5.5, Claude Fable 5.1. License: Commercial use of outputs permitted per Anthropic's usage policies.

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