Cheap Claude API: get Claude Opus, Sonnet and Haiku at 50% off

If you build with Claude, you've probably noticed how quickly the bill grows. Agents and coding tools send long prompts on every turn, and Claude's output tokens are priced several times higher than its input. Developers searching for a cheap Claude API usually want one thing: the same Claude model, with the same quality, for less money. That's achievable, and it doesn't involve switching to a weaker model.

All prices below are per million tokens, taken from the GreenTokens catalogue at the time of writing, next to the official list price for each model.

What the Claude API officially costs

Anthropic prices every Claude model by input and output tokens. The larger the model, the higher the price, and output always costs five times the input. Here's the current lineup at list price:

Notice that newer isn't always pricier. Claude Opus 5.5 has a lower list price than Claude Opus 5, and Claude Sonnet 5 is cheaper than Sonnet 4.6. If you're still on an older model, simply moving to its successor can lower your costs before you do anything else.

The cheapest way to get the same Claude models

Discounted API providers sell access to the same Claude models below the official price. The model is unchanged: the same weights answering the same request. What changes is the price per token. On GreenTokens, most Claude models are 50% below list, and the newest Fable models are 40% below:

Cached input is discounted too. Claude Sonnet 5 bills cache reads at $0.10 per million tokens on GreenTokens, a tenth of its already-discounted input price, which matters a great deal for agents that resend the same long context on every turn.

Switching takes one line

A cheap Claude API is only useful if it doesn't force you to rewrite your code. GreenTokens speaks the Anthropic Messages API natively, including streaming, tool use, extended thinking and prompt caching, so the official Anthropic SDKs work as they are. You change the base URL to https://api.greentokens.io, use a GreenTokens key, and keep the same model names.

It also serves the OpenAI Chat Completions and Responses formats, so tools that only speak OpenAI can call Claude models too. That's handy when one codebase uses both families.

Cheaper Claude Code

Claude Code is often the biggest Claude bill a developer has, because agentic sessions read files, run tools and loop many times per task. It can run on GreenTokens with two environment variables: set ANTHROPIC_BASE_URL to https://api.greentokens.io and ANTHROPIC_AUTH_TOKEN to your key. The Claude Code page in our docs also shows how to map its Opus, Sonnet and Haiku slots to specific models.

Two settings make a noticeable difference. Point the Haiku slot, which Claude Code uses for small background tasks, at Claude Haiku 4.5 rather than a larger model. And give Claude Code its own API key with a daily spend limit, so a long autonomous session can't run past the budget you set.

Three ways to cut your Claude bill further

1. Use the smallest Claude model that does the job. Claude Haiku 4.5 costs a quarter of Claude Opus 5.5 per output token; test it on your real prompts before assuming you need Opus.
2. Cache what repeats. Mark long, stable system prompts and reference documents with cache_control so later calls read them at the cached price.
3. Cap output. Set max_tokens to what the task needs and ask for concise answers; output is where most of a Claude bill goes.

What to check in any cheap Claude API

Not every offer is what it seems, so apply a simple checklist before moving production traffic:

• The model is the real one: the response should echo the exact Claude model you asked for.
• The official price is shown next to the discounted one, so the saving is visible rather than claimed.
• Features you depend on work: streaming, tool use, prompt caching and extended thinking.
• There's no subscription or minimum you have to commit to before trying it.
• Your prompts aren't stored. GreenTokens never stores prompts or model outputs, only the metadata needed for billing.

Common questions

Is a discounted Claude API the same model?

It should be, and you can check. The request names a specific Claude model, the response echoes that exact model, and the behaviour, context window and features match the official API. A provider that quietly swaps in a cheaper model would show it in quality and in the model name it returns.

Are there cheap Claude API credits or keys?

Be wary of anyone selling Claude API keys or credits outright. Keys tied to someone else's account can be revoked at any moment and put your data in unknown hands. A legitimate provider gives you your own key on your own account, with your own balance.

Getting started

Sign in with your email, top up a prepaid balance with crypto, create an API key, and point your Anthropic SDK or Claude Code at GreenTokens. There's no subscription, and every Claude model's official price is listed beside ours on the models page, so you can see exactly what you save before you send a single request.