Predictable AI costs
for vibe coders.
Flat monthly rates for simple structured tasks — JSON, classification, extraction, short generation. Around 30–50% cheaper than OpenAI mini and Anthropic Haiku, with zero surprise bills.
OpenAI-compatible API · Drop-in replacement · Cancel anytime
Trusted by builders shipping on
AI costs are eating your runway.
You ship a feature. Users love it. Then the invoice arrives — thousands of tiny structured calls priced like they're doing serious reasoning. Credits burn. Tokens surprise. Your margins evaporate.
A viral tweet becomes a five-figure invoice. You can't quote pricing to your own users.
You're paying frontier prices to classify support tickets or fill JSON schemas.
Every deploy is a gamble. Every retry costs money. Every user is a liability.
One flat rate. Structured tasks only.
Simplex is purpose-built for the 80% of AI calls in your app that are simple and repetitive — schema-locked JSON, classification, extraction, short replies, routing. We optimize the model, the runtime, and the billing model around exactly this.
- Predictable monthly quotas — never a surprise bill
- JSON schema enforcement by default (100% valid)
- OpenAI-compatible — swap one URL, done
- Live usage dashboard with cost projections
Illustrative — see the cost calculator for your workload.
Three steps to predictable AI.
Grab an API key
Sign up, name your project, copy your key. Under a minute.
Point your SDK
Change the base URL to api.simplex.ai/v1. Keep your OpenAI client.
Ship with confidence
Watch usage in real time. Your bill matches your plan.
Built for the tasks you actually run.
Flat monthly pricing
Know your bill before the month starts.
Purpose-built runtime
Optimized for short structured calls, not long essays.
Schema-enforced JSON
Every response validates against your schema — or errors clean.
Rate-limit headers
Standard headers your framework already understands.
Live usage & projections
See exactly what you'll pay before the month ends.
SOC2 track & EU hosting
Enterprise-grade infra without enterprise-grade pricing.
Same SDK. Better bill.
If you've used the OpenAI SDK, you already know Simplex. Point baseURL at us, keep the rest of your code exactly the same, and cut your inference cost in half.
import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.SIMPLEX_API_KEY,
baseURL: "https://api.simplex.ai/v1",
});
const res = await client.chat.completions.create({
model: "simplex-structured-1",
messages: [
{ role: "system", content: "Extract the user's intent." },
{ role: "user", content: "book me a table for 4 tomorrow at 7" },
],
response_format: {
type: "json_schema",
json_schema: {
name: "intent",
schema: {
type: "object",
properties: {
intent: { type: "string" },
party_size: { type: "number" },
when: { type: "string" },
},
required: ["intent", "party_size", "when"],
},
},
},
});Stop guessing what your app will cost.
Get 5,000 calls/month free, forever. Upgrade when you outgrow it — never before.