Every time I needed to turn an API response into a CSV, or paste a JSON blob out of ChatGPT into something usable, I ended up on a tool site that either wanted me to upload my data, buried the tool under 15 ads, or choked on quoted fields.

So I built JSONSheet — 22 converters that run 100% in your browser . No upload. No signup. No server-side processing at all.

What it does

JSON ↔ CSV with proper RFC 4180 parsing (quoted fields, embedded commas/newlines, escaped quotes)

JSON ↔ YAML — clean block-style output, correct quoting of ambiguous values

JSON → XML and JSON → JSONL (NDJSON) for pipelines and fine-tuning datasets

JSON ↔ Markdown tables — for READMEs, Notion, GitHub issues

CSV/JSON → SQL INSERTs (Postgres & MySQL, with CREATE TABLE + type inference)

JSON → TypeScript interfaces — nested objects become named interfaces

Flatten / unflatten JSON to dot-notation paths

JSON escape/unescape , Base64 encode/decode (UTF-8 safe), TSV → JSON (paste straight from Excel/Sheets), CSV dedupe & transpose ,…