JSON

A lightweight data format built from nested key-value pairs — and a specific trap it's easy to fall into when converting text case carelessly.

What it is

JSON (JavaScript Object Notation) is a lightweight, text-based format for structuring data as key-value pairs, nested inside objects and arrays. Despite the name, it's language-independent — virtually every programming language can read and write it — and it's the dominant format for data exchanged between web APIs and applications.

{"userName": "ana", "roles": ["admin", "editor"]}

Why key casing matters

JSON itself doesn't require any particular capitalization convention for its keys, but the systems that produce and consume JSON usually do. JavaScript-heavy APIs conventionally use camelCase keys (userName); Python-heavy APIs more often use snake_case (user_name). Mismatched conventions between a frontend and backend are a common source of integration bugs — one side expecting userName, the other sending user_name.

Why blindly text-converting a JSON file is risky

JSON's structure depends on exact characters — braces, colons, commas, quotation marks — that a plain case converter has no way of distinguishing from actual content. Running a whole JSON document through a line-by-line text converter risks recasing not just the keys you meant to change, but string values, and potentially mangling the syntax itself if it isn't parsing the structure. Converting JSON key casing safely requires a tool that actually understands JSON's structure — walking the object and renaming only the keys — not a generic text converter.

How this site handles it

The bulk file converter deliberately does not accept .json as a supported upload format, for exactly this reason — its supported formats (.txt, .md, .csv, .docx) are all ones where line-by-line conversion is structurally safe. For converting the case of a single key or value, the main converter's camelCase and snake_case modes work fine on that isolated string; for reshaping an entire JSON document's keys, a small script that actually parses the JSON is the more reliable tool for the job.

Source

RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format, IETF.

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