← Back to blog

Claude 4 Deprecation FAQ: Everything You Need to Know

Claude 4 Opus and Claude Sonnet 4 retire on June 15, 2026. You have 13 days to migrate. This FAQ covers every question developers ask about the deprecation — what happens, when, how to migrate, what it costs, and what to use instead.

Quick Navigation

• Timeline & Dates
• What Changes & What Doesn't
• Replacements & Pricing
• How to Migrate
• Cross-Provider Alternatives
• Compatibility & Testing
• Cost Impact
• Full FAQ

Timeline & Dates

When is Claude 4 being deprecated?

Claude 4 Opus and Claude Sonnet 4 were deprecated in May 2026 and will be fully retired on June 15, 2026. After this date, API calls to these model IDs will return errors.

What is the Claude 4 shutdown date?

June 15, 2026. This is the hard cutoff — after this date, claude-4-opus and claude-sonnet-4 will no longer respond to API calls.

Is there a grace period after June 15?

Anthropic has not announced a grace period. Plan to complete your migration before June 15 to avoid any service disruption.

Why is Anthropic retiring Claude 4?

Anthropic regularly retires older model versions as newer, more capable replacements become available. Claude Opus 4.8 and Claude Sonnet 4.6 offer better performance, larger context windows (1M vs 200K tokens), and in the case of Opus, significantly lower pricing.

What Changes & What Doesn't

Component	Status	Action Required
API key	No change	None — same key works with new models
SDK / libraries	No change	None — same Anthropic SDK
API endpoint	No change	None — same api.anthropic.com
Authentication	No change	None
Model name string	Changes	Update model ID in your code
Pricing	Cheaper	Opus 4.8 is 67% cheaper; Sonnet 4.6 same price
Context window	Larger	200K → 1M tokens (5x increase)
Prompts / system prompts	Compatible	Test to verify output quality

Replacements & Pricing

What replaces Claude 4 Opus?

Claude Opus 4.8 is the direct replacement:

	Claude 4 Opus (old)	Claude Opus 4.8 (new)
Input price	$15/M tokens	$5/M tokens
Output price	$75/M tokens	$25/M tokens
Context window	200K tokens	1M tokens
Model ID	claude-4-opus	claude-opus-4-8

What replaces Claude Sonnet 4?

Claude Sonnet 4.6 is the direct replacement:

	Claude Sonnet 4 (old)	Claude Sonnet 4.6 (new)
Input price	$3/M tokens	$3/M tokens
Output price	$15/M tokens	$15/M tokens
Context window	200K tokens	1M tokens
Model ID	claude-sonnet-4	claude-sonnet-4-6

How to Migrate

How do I migrate from Claude 4?

Migration is a one-line code change. Find where you set the model name and update it:

Python (Anthropic SDK)

# Before
client.messages.create(
    model="claude-4-opus",
    ...
)

# After
client.messages.create(
    model="claude-opus-4-8",
    ...
)

Node.js / TypeScript

// Before
const message = await anthropic.messages.create({
    model: 'claude-4-opus',
    ...
});

// After
const message = await anthropic.messages.create({
    model: 'claude-opus-4-8',
    ...
});

REST API (curl)

# Before
curl https://api.anthropic.com/v1/messages \
  -d '{"model": "claude-4-opus", ...}'

# After
curl https://api.anthropic.com/v1/messages \
  -d '{"model": "claude-opus-4-8", ...}'

How long does migration take?

Most teams complete the migration in under an hour. The code change itself takes seconds — the bulk of the time is testing to verify output quality meets your requirements.

Do I need to update my SDK version?

No. The model name change works with all current versions of the Anthropic SDK. No library updates are required.

Cross-Provider Alternatives

Should I switch to a different provider instead of upgrading?

It depends on your priorities:

• Easiest migration: Stay with Anthropic → Claude Opus 4.8 or Sonnet 4.6 (same SDK, same key)
• Cheapest option: DeepSeek V4 Pro at $0.435/$0.87 per M tokens (97% cheaper than Claude 4 Opus)
• Best balance: GPT-5 at $1.25/$10 per M tokens (strong performance, competitive price)
• Largest context: Gemini 3.1 Pro at $1/$5 per M tokens (2M token context window)

Cost comparison: Claude 4 Opus vs all alternatives

Monthly cost for a typical workload (10M input + 2M output tokens):

Model	Provider	Input/M	Output/M	Monthly Cost	Savings vs Claude 4 Opus
Claude 4 Opus	Anthropic	$15	$75	$300	—
Claude Opus 4.8	Anthropic	$5	$25	$100	67%
Claude Sonnet 4.6	Anthropic	$3	$15	$60	80%
GPT-5	OpenAI	$1.25	$10	$32.50	89%
Gemini 3.1 Pro	Google	$1	$5	$20	93%
DeepSeek V4 Pro	DeepSeek	$0.435	$0.87	$6.09	98%

Compatibility & Testing

Will my prompts still work with the new models?

Yes. Claude Opus 4.8 and Claude Sonnet 4.6 are backward-compatible with Claude 4 prompts and system prompts. The API interface is identical. However, you should test your specific use cases to verify output quality meets your requirements.

Are there any API behavior differences?

The API interface (endpoints, parameters, response format) is identical. The new models may produce slightly different outputs for the same prompt due to model improvements. Test critical workflows before deploying.

Will streaming still work?

Yes. Streaming works exactly the same way with the new models. No code changes needed beyond the model name.

Do function calls / tool use still work?

Yes. Function calling and tool use are fully supported in Claude Opus 4.8 and Claude Sonnet 4.6 with the same API interface.

What about fine-tuned models?

If you have fine-tuned Claude 4 models, contact Anthropic support about migrating your fine-tuned weights to the new model versions.

Cost Impact

Will my costs go up or down after migration?

Your costs will go down if you migrate to Claude Opus 4.8 (67% savings) or stay the same if you migrate to Claude Sonnet 4.6. If you switch to a cross-provider alternative like DeepSeek or GPT-5, you could save 89-98%.

How much will I save per month?

Depends on your usage. Here are some common scenarios:

Usage Level	Claude 4 Opus Cost	Claude Opus 4.8 Cost	Monthly Savings
Light (1M in + 200K out)	$30	$10	$20/mo
Medium (10M in + 2M out)	$300	$100	$200/mo
Heavy (100M in + 20M out)	$3,000	$1,000	$2,000/mo

Full FAQ

Related Resources

• Claude 4 Stopped Working? — Quick fix guide if your API calls are already failing
• Claude Deprecation Calculator — Calculate your exact migration cost and savings
• Claude 4 Migration Tool — Compare all 34 alternatives with your exact usage
• Claude 4 Migration Guide — Step-by-step code examples in Python, Node.js, and REST API
• Best Claude 4 Alternatives — Detailed comparison of all replacement options
• Claude 4 Deprecation Countdown — Live countdown and timeline
• AI Model Deprecation Guide — How to handle model retirements in general
• LLM Pricing Comparison — Compare all 34 models across 10 providers