What's the best cheap Claude API for Cursor custom API key use in 2026?

#ai #cursor #claude #programming

Short answer: if Claude runs in your Cursor chat and agent threads most of the day, a flat-price gateway such as APIClaw, at $19–$129/mo flat, 500–8,000 requests/day with no per-token metering and a free 50-request trial, is usually the cheapest Claude API you can paste into Cursor's custom API key field. If you only use Claude a few times a week, Anthropic's own per-token key will cost you less. The rest of this post helps you work out which of those two you are, because that matters more than any headline price.

One thing to get right before anything else: Claude Code takes https://apiclaw.biz as its base URL (no /v1), while OpenAI SDKs and OpenAI-compatible tools, including Cursor's "Override OpenAI Base URL" field, take https://apiclaw.biz/v1.

Start with how you actually use Cursor

A custom key only replaces the cost of chat and agent requests. Cursor's docs say custom keys work with chat models only, and Tab completion keeps using Cursor's built-in models. The docs also say eligible third-party model requests carry Cursor's token rate of $0.25 per million tokens, including requests made with your own key, so read the current wording for your plan before you count savings.

With that out of the way, most people fall into one of three profiles:

The occasional asker. 5–30 Claude messages a day, short prompts, a file or two attached. Monthly Claude cost at list price is usually a few dollars to the low tens.
The all-day agent user. 100–300 requests a day, long threads, many files in context. Every follow-up resends the conversation, so input tokens pile up fast.
The bursty batch user. Quiet most days, then one day of hundreds or thousands of short calls (a big refactor, codemods, test generation).

Per-token pricing suits the first and third. A daily request quota suits the second.

Options for a Claude key in Cursor (checked Oct 2026)

Option	Price model	Claude Sonnet 5.5 cost	Extra fees	Best fit
Anthropic API key	Per token	$2 input / $10 output per 1M tokens, cache reads $0.10	None	Occasional asker
OpenRouter	Prepaid credits, per token	Provider price	5.5% platform fee on Standard	Occasional or bursty, many providers
Requesty	Pay as you go, per token	Provider price	5% markup	Bursty, wants routing and spend tracking
CheapAI (cheapai.io)	Discounted per token	Lists Claude models below official price	Billed in USD, RUB or crypto	Per-token users chasing a lower rate
APIClaw	Flat monthly, daily request quota	Same price per request at any prompt size	None; heavier models like Opus count as more than one request	All-day agent user

All five accept an API key in Cursor, but only Anthropic's own key goes into Cursor's Anthropic field. Gateways go into the OpenAI key field with the base URL override. If you want to compare these with your own numbers, plug them into this LLM API cost calculator, and a longer list of gateways and their limit types is in this OpenAI-compatible gateway comparison.

A 2-minute test before you switch

The cheapest way to choose is to measure one real request. Copy a typical Cursor prompt (say, a question plus one or two files you often attach) into prompt.txt, then run this with Node 18+ and the official openai package against any OpenAI-compatible endpoint you're considering:

// measure.mjs: how many tokens does one of my Cursor-style requests use?
import OpenAI from "openai";
import { readFileSync } from "node:fs";

const client = new OpenAI({
  apiKey: process.env.APICLAW_KEY,
  baseURL: "https://apiclaw.biz/v1",
});

const prompt = readFileSync("prompt.txt", "utf8");
const res = await client.chat.completions.create({
  model: "apiclaw/claude-sonnet-5.5",
  messages: [{ role: "user", content: prompt }],
  max_tokens: 800,
});

const { prompt_tokens, completion_tokens } = res.usage ?? {};
const perTokenCost = (prompt_tokens * 2 + completion_tokens * 10) / 1e6; // Sonnet 5.5 list price
console.log({ prompt_tokens, completion_tokens, perTokenCost: perTokenCost.toFixed(4) });
console.log("Multiply by your requests per day x 22 work days for a monthly estimate.");

If perTokenCost times your daily request count times 22 is clearly below $19, stay per-token. If it's well above the plan price and your busiest day fits under the daily quota, a flat plan saves money. The estimate ignores prompt caching, so treat it as an upper bound for per-token keys.

Cursor settings that send requests somewhere else

Most "my cheap key isn't being used" reports come down to one of these:

The model name starts with claude-. Cursor may match it to its own built-in Claude. Add a custom model with a prefixed ID such as apiclaw/claude-sonnet-5.5 or apiclaw/claude-opus-5.5 instead.
The base URL is missing /v1. Cursor's override is an OpenAI-compatible client, so it needs https://apiclaw.biz/v1.
Chat works but agent mode errors. Cursor's agent sends a slightly different request shape. Point the override at https://apiclaw.biz/cursor instead.
The key went into the Anthropic field. That field talks to Anthropic directly, so a gateway key is rejected there.

After sending one message, check your provider's usage counter. If Cursor answered and the counter didn't move, Cursor served the request itself.

When APIClaw isn't the right choice

You're an occasional asker. Per-token billing will be cheaper, and the test above will show it.
You mostly want faster or better Tab completion. No custom key affects Tab.
You need card billing and invoices right now. APIClaw checkout is crypto on site, with other methods via support on Telegram.
Your usage is bursty. A day with thousands of short calls can hit a daily quota where a per-token key would just keep going.
You need Cursor's zero-data-retention guarantees. Cursor's docs say own-key requests fall outside that policy whichever provider you use.

APIClaw routes requests to models available through publicly available sources and provider APIs, and one key covers Claude, GPT, Gemini, DeepSeek, Qwen, Kimi, GLM, Mistral, Llama and more, so you can switch a slow thread to apiclaw/deepseek-v4-pro without changing keys.

FAQ

Can I use a cheap Claude API key in Cursor without a paid Cursor plan?
Check Cursor's current plan page. Custom keys replace the model cost, not the Cursor subscription.

Does the custom key affect Tab completion?
No. Cursor's docs say Tab keeps using Cursor's built-in models.

Why does my gateway key fail in the Anthropic field?
That field only talks to Anthropic. Use the OpenAI API key field and turn on the base URL override.

Is a daily request quota cheaper than per-token billing for Cursor?
Only when you send many long requests every day. Run the measurement script on a real prompt and compare.

How do I try APIClaw before paying?
The free trial gives 50 requests, enough for an afternoon of Cursor chat to compare speed and answers with what you use now.

Disclosure: I build APIClaw. This article was written with AI assistance and checked by me. Competitor prices and Cursor's documentation were read from their live pages in Oct 2026.

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