API monetization platform for teams that sell an API

1. 1

   Step 1: Add the SDK to your API

   A few lines of middleware. Keys and limits are checked in your process.

   server.jsCopy

   import express from "express";
   import { usageRail } from "@usagerail/node/express";
   
   const app = express();
   
   // Checks the API key, rate limit and quota
   app.use(usageRail({
     appKey: process.env.USAGERAIL_APP_KEY,
     auth: "api-key",
   }));
   
   app.post("/v1/verify", verifyEmail);

2. 2

   Step 2: Customers create their own keys

   In a portal on your domain, with your plans and your branding.

   developers.mailcheck.dev/keys

   API keys

   Create key

   ProductionCreated just now

   mck_live_k7Gx2PqA4vR9tLwQe2ZsXb7nJc3MyHd8KfP1aUo629139iCopy

   Shown once. Copy it now.

   Pro plan, this month78,214 of 100,000
3. 3

   Step 3: Usage is billed through your Stripe

   Once per period, with the included requests already applied.

   Mailcheck API

   Invoice MCK-0042

   Oct 1 to Nov 1, 2026

   Pro plan

   $29.00

   Pro usage128,400 requests, first 100,000 included

   $14.20

   Total

   $43.20

   Charged to the card on file by Stripe

Example plan: $29 a month with 100,000 requests included, then $0.50 per 1,000.