Skip to content
OfferSign up and get $10 of credit for any model in Chat and the API. Top up from $1, with no processing fees. See free models →·Some free models are at the daily cap — refills 05:30 IST; requests auto-route to a live backup. Status →
One AI API Key

Anthropic · Claude · Flagship

Claude Fable 5.1 (free lane)

New

Claude Fable 5.1 on the free lane for long agent runs, front-end code and analysis.

Model id

claude-fable-5-1:free

Price per 1M tokens

Input
$7.00
Output
$35.00
Cached input
Not offered

Added here 11 Nov 2026 — read the changelog for what changed and why.

Output is 5× the input rate. $1 covers about 40 prompts of 1,000 input + 500 output tokens. 1 credit = $1 of usage. All rates

Start using Claude Fable 5.1 (free lane)

Set ONEAIAPIKEY_API_KEY to a key from your console, then run any example. Streaming is on so long answers are not cut off by idle-connection timeouts.

curl https://api.oneaiapikey.com/v1/chat/completions \
  -H "Authorization: Bearer $ONEAIAPIKEY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-fable-5-1:free",
    "stream": true,
    "messages": [{"role": "user", "content": "Add rate limiting to the login route, update the tests and run them."}]
  }'
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.oneaiapikey.com/v1",
    api_key=os.environ["ONEAIAPIKEY_API_KEY"],
)

stream = client.chat.completions.create(
    model="claude-fable-5-1:free",
    messages=[{"role": "user", "content": "Add rate limiting to the login route, update the tests and run them."}],
    stream=True,  # recommended for long outputs
)
for chunk in stream:
    if chunk.choices and chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="", flush=True)
import OpenAI from "openai";

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

const stream = await client.chat.completions.create({
  model: "claude-fable-5-1:free",
  messages: [{ role: "user", content: "Add rate limiting to the login route, update the tests and run them." }],
  stream: true,
});

for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content ?? "");
}

More: quickstart · API reference · try it in Chat first

Tokens per day, by model

Last 7 days, UTC days

Hover, tap or drag across any day, or focus the chart and use the arrow keys, to see how every model did that day.

Real tokens served through this gateway, updated every 5 minutes. Ranked by usage, not quality.

Full ranking insights

Claude line-up

Claude Fable 5.1 (free lane) or Claude Fable 5.1 or GPT-5.6 Sol?

Of the 9 Claude models on this site, Claude Fable 5.1 (free lane) is the top of the line-up and Claude Fable 5.1 the step down. GPT-5.6 Sol from OpenAI is the closest-priced flagship-tier model from another vendor. Each comparison lists the published rates and limits, then what favours each side.

Claude Fable 5.1 (free lane)vsClaude Fable 5.1

Per 1M tokensClaude Fable 5.1 (free lane)Claude Fable 5.1
Input$7the same$7
Output$35the same$35
Context1Mthe same1M
Max output128kthe same128k

Pick Claude Fable 5.1 (free lane) when

Nothing in the published data puts it ahead of Claude Fable 5.1.

Pick Claude Fable 5.1 instead when

  • Claude Fable 5.1 (free lane) does not list Prompt caching and your code depends on it.

Claude Fable 5.1 (free lane)vsGPT-5.6 Sol

Per 1M tokensClaude Fable 5.1 (free lane)GPT-5.6 Sol
Input$775% more$4
Output$3575% more$20
Context1M5% smaller1.05M
Max output128kthe same128k

Pick Claude Fable 5.1 (free lane) when

  • the work is long agent runs, front-end code and analysis, which this catalogue lists for Claude Fable 5.1 (free lane) and not for GPT-5.6 Sol.

Pick GPT-5.6 Sol instead when

  • the job runs well enough on the lower rates: input at 43% less and output at 43% less.
  • inputs outgrow the 1M-token window of Claude Fable 5.1 (free lane); GPT-5.6 Sol accepts 1.05M.
  • Claude Fable 5.1 (free lane) does not list JSON mode and Prompt caching and your code depends on it.
  • your workload looks like hard reasoning, planning and math, labels the catalogue gives GPT-5.6 Sol only.

Use cases

What Claude Fable 5.1 (free lane) is listed for, and what it costs

The catalogue lists Claude Fable 5.1 (free lane) for long agent runs, front-end code and analysis. Each row prices one typical request at the published rates, with the arithmetic shown. Token counts are examples; your prompts will differ.

Model your own traffic

  1. Long agent runs

    One turn of a long agent session: 60,000 tokens of context, and 3,000 tokens of edits and tool calls back.

    “Add rate limiting to the login route, update the tests and run them.”

    Same request on Claude Fable 5.1 $0.1875 and GPT-5.6 Sol $0.12. Cheapest flagship-tier model in the family: Claude Opus 5.5 at $0.08, 85% less.

    $0.525

    per agent turn, about 19 per $10

    0.06 × $7 + 0.003 × $35

  2. Front-end code

    A UI component from a description: 6,000 tokens of existing components and styles in, 2,500 tokens of markup and code out.

    “Build a responsive pricing table component in React with a monthly and yearly toggle.”

    Same request on Claude Fable 5.1 $0.1295 and GPT-5.6 Sol $0.074. Cheapest flagship-tier model in the family: Claude Opus 5.5 at $0.0518, 60% less.

    $0.1295

    per component, about 77 per $10

    0.006 × $7 + 0.0025 × $35

  3. Analysis

    A hard question with its supporting material: 8,000 tokens in, 4,000 tokens out including the reasoning.

    “Given these three incident timelines, find the shared root cause and the evidence for it.”

    Same request on Claude Fable 5.1 $0.196 and GPT-5.6 Sol $0.112. Cheapest flagship-tier model in the family: Claude Opus 5.5 at $0.0784, 60% less.

    $0.196

    per answer, about 51 per $10

    0.008 × $7 + 0.004 × $35

Overview

When Claude Fable 5.1 (free lane) fits

Claude Fable 5.1 (free lane) is a flagship model from Anthropic, available here under the exact model id “claude-fable-5-1:free”. It heads the Claude line-up here, above Claude Fable 5.1, Claude Opus 5.5 (free lane), Claude Opus 5.5, Claude Sonnet 5, Claude Sonnet 5.5 (free lane), Claude Sonnet 5.5, Claude Haiku 4.5 and Claude Haiku 5.5. Anthropic has not published a release date we can cite; it has been available here since 11 Nov 2026.

Anthropic documents tools, vision, reasoning and structured output for it, and it reads images as well as text.

It costs $7 per million input tokens and $35 per million output tokens, so output is 5× the input rate. On the use cases below, output makes up 20% of the bill for long agent runs, 68% for front-end code and 71% for analysis, so capping max tokens and asking for diffs saves more than trimming the prompt. With a 3:1 input-to-output mix it ranks 26th lowest-cost of the 27 models on this site.

There is no discounted cached-input rate for this model, so every input token bills at $7 per million.

It is served through the OpenAI-compatible format at https://api.oneaiapikey.com/v1, so any SDK or tool that lets you set a custom base URL, for example Codex CLI, Cursor and Cline, can use it. It is not offered on the Anthropic Messages endpoint; pick an Anthropic-format model for Claude Code.

Use Claude Fable 5.1 (free lane) with any balance.

Claude Fable 5.1 (free lane) is a paid model: any balance above $0 pays for it, the $10.00 sign-up credit included. When it runs out, add $1 or more to your wallet. Every request is billed at the rates above, with a receipt in your usage log.

Claude Fable 5.1 (free lane) is developed by Anthropic. Model names and trademarks belong to their owners. One AI API Key is an independent API gateway and is not affiliated with, endorsed by or sponsored by Anthropic.