Deeply nested JSON test file

Handle it in code

Each snippet below was run against this exact file with Python 3.14.4 and Node 24.15.0 when this page was built, and the output shown is what it printed.

Python

Deep nesting exhausts the parser's recursion limit. Catch it, and reject the input as too deep rather than crashing the worker.

import json

try:
    with open("deeply-nested-100000.json", encoding="utf-8") as f:
        json.load(f)
    print("parsed")
except RecursionError:
    print("rejected: nested too deeply to parse")

Run against this file, it prints: rejected: nested too deeply to parse

Node.js

Check whether your runtime copes before trusting it with uploads: a crash here takes the whole process down.

const fs = require('node:fs');

try {
  JSON.parse(fs.readFileSync('deeply-nested-100000.json', 'utf8'));
  console.log('parsed');
} catch (e) {
  console.log('rejected:', e.name, e.message);
}

Run against this file, it prints: parsed