How to Access Claude Fable 5: API, Claude Apps, and Plans

Anthropic shipped Claude Fable 5 on June 9, 2026. If you want to use it today, you have two practical options: call it through the Claude API or use it inside eligible Claude subscription plans during the launch window. This guide shows which route to choose, how to make your first API request, what changes after June 22, and how Claude Mythos 5 differs from Fable 5. If you have used Anthropic’s recent releases before, the workflow is similar to getting started with the Claude Opus 4.8 API.

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Claude Fable 5 is the new public flagship model. Claude Mythos 5 is a related restricted model that most developers cannot access. This article focuses on the paths you can actually use, then explains where Mythos 5 fits.

TL;DR

Claude Fable 5 is available now through the Claude API with the model ID claude-fable-5.

From June 9 to June 22, 2026, it is also included at no extra cost on Pro, Max, Team, and seat-based Enterprise plans. Starting June 23, 2026, it leaves those included plans and requires usage credits. Claude Mythos 5 remains restricted and has no public sign-up.

Choose your access route

Use this table to decide how to access Claude Fable 5.

Access route	Best for	Cost	Availability
Claude API with claude-fable-5	Developers building apps, scripts, agents, and integrations	$10 / million input tokens, $50 / million output tokens; fully available on consumption-based Enterprise plans	Available now
Pro, Max, Team, and seat-based Enterprise plans	Existing Claude app users	Included at no extra cost during launch window	June 9 to June 22, 2026; usage credits required from June 23

If you are writing code, use the API. It gives you a stable model ID and works through the standard Messages API.

If you mainly use Claude through the web, desktop, or mobile app, use the subscription route during the free launch window. Many teams use both: Claude apps for ad-hoc work and the API for scheduled jobs, internal tools, or product features.

For model background and comparisons, see what Claude Fable 5 is. This guide stays focused on access and implementation.

Access Claude Fable 5 through the Claude API

The API route requires three things:

1. An Anthropic account
2. An API key
3. The model ID: claude-fable-5

Step 1: Create an Anthropic API key

Go to the Anthropic Console, then sign in or create an account.

In the console:

1. Open the API keys section.
2. Create a new key.
3. Copy it immediately.
4. Store it in a password manager or secrets vault.

You only see the full key once. If you work in an organization, make sure you create the key under the correct workspace instead of your personal default workspace.

API billing is consumption-based. Claude Fable 5 costs:

• $10 per million input tokens
• $50 per million output tokens

For a deeper pricing breakdown, see Claude Fable 5 pricing. The structure is similar to Claude Opus 4.8 pricing.

Step 2: Set ANTHROPIC_API_KEY

Anthropic tooling commonly reads your key from an environment variable named ANTHROPIC_API_KEY.

On macOS or Linux:

export ANTHROPIC_API_KEY="your-key-here"

On Windows PowerShell:

$env:ANTHROPIC_API_KEY = "your-key-here"

For production or team projects, do not hardcode the key. Use a .env file, CI/CD secret, cloud secret manager, or another managed secret store.

Step 3: Send your first request

Use the standard Messages API endpoint:

https://api.anthropic.com/v1/messages

Required headers:

• x-api-key
• anthropic-version: 2023-06-01
• content-type: application/json

Minimal curl request:

curl https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{
    "model": "claude-fable-5",
    "max_tokens": 1024,
    "messages": [
      {
        "role": "user",
        "content": "Hello, Fable 5"
      }
    ]
  }'

If the request succeeds, you receive a JSON response containing the model’s reply.

Common errors:

Error	Likely cause	Fix
401	API key is missing, invalid, or unset	Check ANTHROPIC_API_KEY and regenerate the key if needed
404 on model	Model ID typo or workspace lacks access	Confirm claude-fable-5 spelling and workspace access
Billing/access error	Account is not configured for API usage	Check billing and organization settings in the console

You can confirm the latest model ID and capabilities in the official Anthropic models overview.

For streaming, system prompts, tool use, and production patterns, see the full Claude Fable 5 API how-to.

Access Claude Fable 5 through Claude plans

If you already subscribe to Claude, you may have Fable 5 in the Claude apps without using the API.

From June 9 through June 22, 2026, Anthropic includes Claude Fable 5 at no extra cost on:

• Pro
• Max
• Team
• Seat-based Enterprise plans

During this window, select Fable 5 from the model picker in the Claude web, desktop, or mobile app. Usage counts against your normal plan usage rather than a separate bill.

What changes on June 23, 2026

The free inclusion is temporary.

On June 23, 2026:

• Fable 5 is removed from included access on Pro, Max, Team, and seat-based Enterprise plans.
• Using Fable 5 on those plans requires usage credits.
• The API route remains available at standard token rates.

Anthropic has said it plans to restore some standard access on these plans when capacity allows, but there is no firm date. If your team depends on Fable 5, plan for usage credits after June 22.

Important distinction:

• Seat-based Enterprise plans are affected by the June 23 plan-access change.
• Consumption-based Enterprise plans access Fable 5 through usage, similar to the API.

Your Claude app subscription and API usage are separate. An API key bills independently from your app plan, so production systems should use the API if you need predictable programmatic access.

For practical ways to reduce cost, see using Claude Fable 5 for free. Similar usage-management ideas also apply from using Claude Opus 4.8 for free.

Can you access Claude Mythos 5?

For most developers, no.

Claude Mythos 5 is a restricted sibling model to Fable 5. It runs on the same underlying model as Fable 5, but with some safeguards lifted, which is why access is locked down.

Current access is limited to a small group through Project Glasswing, a collaboration with the US government. That group includes cyberdefenders and infrastructure providers. For them, cyber safeguards are lifted so they can perform defensive security work that the public model would route away from.

Anthropic has also said biology researchers will get access soon, with biology and chemistry safeguards removed for that group while cyber safeguards remain on. Existing Claude Mythos Preview users can upgrade to Mythos 5.

There is no public sign-up form. You cannot get Mythos 5 through a normal Claude plan or by creating an API key. Anthropic has described a broader trusted-access program, but it is not open yet.

For details, read Anthropic’s Claude Fable 5 and Mythos 5 announcement.

Practical takeaway: build against Fable 5. It is the model available to public developers.

Understand Fable 5 routing behavior

Before building on Fable 5, account for one important behavior: some sensitive queries are not answered by Fable 5 directly.

Queries involving these areas may be routed to Claude Opus 4.8:

• Cybersecurity
• Biology and chemistry
• Model distillation

The response still comes back through the same API call, but the model handling that specific turn may be Opus 4.8, where the relevant safeguards apply.

Anthropic reports that this safeguard routing triggers in fewer than 5% of sessions, so most workloads will not see it. But if you build in a sensitive domain and responses feel different from expected, routing may be the reason.

Implementation tip: log the model field returned in API responses. That gives you visibility into whether a request was handled by Fable 5 or routed elsewhere.

For context on the routed model, see what Claude Opus 4.8 is.

Test Claude Fable 5 access with Apidog

Before integrating Fable 5 into an app, verify that your API key and workspace can call the model. The fastest way is to send one real request from an API client and inspect the response.

Apidog works well for this because you can configure the request once, save it, share it with your team, and generate client code from it.

Create a test request in Apidog

1. Create a new HTTP request.
2. Set the method to POST.
3. Use this URL:

https://api.anthropic.com/v1/messages

1. Add these headers:

x-api-key: your-api-key
anthropic-version: 2023-06-01
content-type: application/json

1. Add this JSON body:

{
  "model": "claude-fable-5",
  "max_tokens": 1024,
  "messages": [
    {
      "role": "user",
      "content": "Hello, Fable 5"
    }
  ]
}

1. Send the request.

A clean 200 response with a model reply confirms that your API key and workspace have access.

If you see an error:

• 401: check the API key.
• 404: check the model ID and workspace access.
• Other access or billing errors: check your Anthropic account settings.

For team usage, save the request to a collection. Store the API key as an Apidog environment variable instead of pasting it into a shared request body.

If you want to test streaming, add streaming to the request body and verify that Apidog renders tokens as they arrive before you implement streaming in your application.

This workflow is similar to testing the ChatGPT API with Apidog. To get started, Download Apidog, create the request above, and export working client code after the call succeeds.

FAQ

Is Claude Fable 5 available now?

Yes. Claude Fable 5 launched on June 9, 2026. It is available through the Claude API with the model ID claude-fable-5.

It is also included in Claude apps for Pro, Max, Team, and seat-based Enterprise subscribers from June 9 to June 22, 2026.

Do I need to pay to access Fable 5?

It depends on the route.

Through the API, you pay per token:

• $10 per million input tokens
• $50 per million output tokens

Through Pro, Max, Team, or seat-based Enterprise plans, Fable 5 is included from June 9 to June 22, 2026. After June 22, that plan route requires usage credits.

How do I access Fable 5 after June 23?

Starting June 23, 2026, Fable 5 is no longer included on Pro, Max, Team, and seat-based Enterprise plans. You need usage credits to use it through those plans.

The API route is unaffected. You can continue calling claude-fable-5 at the standard token rates.

Can I access Claude Mythos 5?

Almost certainly not. Claude Mythos 5 is restricted and has no public sign-up.

It is currently available only to a small group through Project Glasswing, with biology researchers expected to get access soon. Existing Claude Mythos Preview users can upgrade. Most developers should build around Fable 5 instead.

What is the Fable 5 API model name?

The model ID is:

claude-fable-5

Pass it in the model field when calling:

https://api.anthropic.com/v1/messages

Which plans include Fable 5?

From June 9 to June 22, 2026, Fable 5 is included at no extra cost on:

• Pro
• Max
• Team
• Seat-based Enterprise plans

Consumption-based Enterprise plans access Fable 5 through usage, similar to the API.

What happens to sensitive queries on Fable 5?

Queries involving cybersecurity, biology and chemistry, or model distillation may be routed to Claude Opus 4.8, where the relevant safeguards apply.

This routing triggers in fewer than 5% of sessions, but you should log the returned model field if your application needs to know which model handled a response.

Do I need separate access for the API and Claude apps?

Yes. Claude app subscriptions and Anthropic API keys are billed and managed separately.

If you are building software, the API is the more predictable long-term route because it is not tied to the temporary app-plan access window.

Next step

If you are building with Claude Fable 5, start with the API:

1. Create an API key in the Anthropic Console.
2. Set ANTHROPIC_API_KEY.
3. Send a test request to claude-fable-5.
4. Verify the response in Apidog.
5. Save the working request and use it as the baseline for your implementation.

If you use Claude mainly through the apps, you can use Fable 5 through June 22 on eligible plans. After that, plan for usage credits unless Anthropic announces broader included access.