I built 3 free APIs for LLM developers — here's what I shipped and why

The Problem

If you've built anything with GPT-4, Claude, or Llama, you've probably run into these:

• JSON that won't parse because of a trailing comma or markdown fence


• Discord webhook URLs exposed in your frontend code


• Needing QR codes dynamically but not wanting to pay per request

I kept hitting these same walls, so I spent a week building three utility APIs to solve them. All three have free tiers on RapidAPI.

1. JSON Repair & Formatter

LLMs don't always return clean JSON. Trailing commas, markdown code fences, truncated objects — all of these break JSON.parse() and crash your pipeline.

Input (broken LLM output):

{ "name": "Pro Plan", "price": 19.00, }

Output (clean JSON):

{ "name": "Pro Plan", "price": 19.00 }

Fast local repair engine first (<5ms, no AI call). Falls back to AI only when the input is too corrupted for local processing.

Free tier: 500 requests/month, no card required.

https://rapidapi.com/kordhubdev/api/kordhub-ai-json-repair-formatter

2. Discord Webhook Shield & Formatter

If you use Discord webhooks in a frontend app, your webhook URL is exposed in source code. Anyone can find it and spam your server.

You register your real webhook URL once — stored encrypted — and get a safe webhook_id instead. Your real URL never touches your frontend again. Auto-strips @everyone/@here spam before anything reaches Discord.

Free tier: 200 messages/month, no card required.

https://rapidapi.com/kordhubdev/api/kordhub-discord-webhook-shield-formatter

3. QR Code Generator

PNG & SVG output, custom hex colors, optional logo overlay. Error correction up to H (30%) keeps the QR scannable even with a logo on top. 100% local processing — no per-call AI cost.

Free tier: 500 requests/month, no card required.

https://rapidapi.com/kordhubdev/api/kordhub-qr-code-generator

Tech stack

FastAPI + Python, hosted on Render. Local engines use open-source libraries (json-repair, qrcode + Pillow) so cost per request is near zero. Groq only kicks in as AI fallback when local processing fails.

Would love feedback on pricing or use cases I missed.

Find me on X: @kordhub