The easiest way to build and test your LLM apps

ChunkBack makes it easy for devs to create repeatable LLM responses, so you can build the best UIs without breaking the budget

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CBPL Simulator
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CBPL Simulator
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How does it work?

ChunkBack is a "deterministic LLM" server, that takes in a custom language and streams back messages in the LLM standard of your choice. Set up in 3 steps below!

1

Get your API Key

Create account, get 1,000 free requests

2

Replace your base URL

Point your app to Chunkback with one line

3

Start Testing

Get deterministic responses, save money

1

Get your API Key

Create account, get 1,000 free requests

2

Replace your base URL

Point your app to Chunkback with one line

3

Start Testing

Get deterministic responses, save money

How does it work?

ChunkBack is a "deterministic LLM" server, that takes in a custom language and streams back messages in the LLM standard of your choice. Set up in 3 steps below!

1

Get your API Key

Create account, get 1,000 free requests

2

Replace your base URL

Point your app to Chunkback with one line

3

Start Testing

Get deterministic responses, save money

1

Get your API Key

Create account, get 1,000 free requests

2

Replace your base URL

Point your app to Chunkback with one line

3

Start Testing

Get deterministic responses, save money

How does it work?

ChunkBack is a "deterministic LLM" server, that takes in a custom language and streams back messages in the LLM standard of your choice. Set up in 3 steps below!

1

Get your API Key

Create account, get 1,000 free requests

2

Replace your base URL

Point your app to Chunkback with one line

3

Start Testing

Get deterministic responses, save money

1

Get your API Key

Create account, get 1,000 free requests

2

Replace your base URL

Point your app to Chunkback with one line

3

Start Testing

Get deterministic responses, save money

For $20 a month, you can save thousands

Experiment with our cost calculator to figure out how much you can save with ChunkBack

Production API Cost

$798

Chunkback Cost

$40

Your Savings

$758

Save 95.0%
ProviderModelInput (per 1M)Output (per 1M)
OpenAIGPT-4o$2.50$10.00
OpenAIo1$15.00$60.00
AnthropicClaude Sonnet 4.5$3.00$15.00
AnthropicClaude Opus 4.1$15.00$75.00
GoogleGemini 2.5 Pro$1.25$5.00
ChunkbackAll Providers$0$0

Chunkback: $20/month for 1M requests. Click a row to update the calculator.

Pricing

Get started for free. No credit card required

Free

$0

1,000 requests/mo

All providers

Community support

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Pro

$20

1M requests/mo

Priority email

99.9% SLA

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Enterprise

Custom

Dedicated support

Custom SLA

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