I built a free JSON Size Calculator — here's why it matters more than I thought

Hey IH community 👋,

I've been building Format JSON Online — a suite of 60+ free JSON tools — and recently shipped a JSON Size Calculator that I initially thought was a "nice to have." Turns out, developers actually care a lot about this.
The problem it solves
When you're building APIs, you usually eyeball payload sizes or rely on Network DevTools after the fact. But by the time you're debugging a sluggish API response or hitting a 413 payload-too-large error, you've already shipped the problem.
The JSON Size Calculator lets you paste your JSON and instantly see:

Exact size in bytes, KB, and MB
Character count, line count, and property count
Nesting depth and complexity score
Formatted vs minified size comparison

All client-side, no data ever leaves your browser.
What surprised me after launching it
The use cases are more diverse than I expected. People are using it to:

Check if their API response fits within service limits (Cloudflare Workers, AWS Lambda, etc.)
Compare verbose vs. optimized JSON structures before shipping
Audit third-party API payloads they're consuming
Size-check config files before committing them

One quick example: using "userIdentifier" vs "id" for a key name across thousands of records is a ~38% size difference. That adds up fast when you're serving millions of requests.
The size guidelines I baked in

< 100 KB → Small, ideal for API responses
100 KB – 1 MB → Medium, consider compression or pagination
1 MB → Large, likely needs optimization

🔗 https://formatjsononline.com/json-size-calculator