Will minifying break my JSON?

No. The tool parses your input and re-serializes valid JSON, so the data is identical — only the representation changes. Whitespace-only mode is fully reversible; key abbreviation changes key names, so update any code that reads them.

How much can I actually save?

Pretty-printed JSON wastes tokens on indentation and newlines. Stripping whitespace alone often saves 20–40% of tokens, and key abbreviation on records with long repeated keys can push total savings past 50%.

When should I not abbreviate keys?

If the model needs to understand the keys semantically — or you ask it to echo them back — keep readable keys. Abbreviation is best for bulk data where the meaning is in the values, and you supply a short key legend once in the prompt.

Is my data sent anywhere?

No. Parsing and minification happen entirely in your browser. Nothing you paste is uploaded, stored or logged.

JSON Prompt Token Minifier

JSON prompt token minifier

When you pass JSON into a prompt, every space, newline and indent is a billable token — on every call. This tool re-serializes your JSON at the minification level you choose and shows exactly how many tokens you save, so you can shrink large payloads without changing a single value.

How it works

The minifier parses your JSON (rejecting invalid input) and rebuilds it:

Whitespace-only — removes all indentation and line breaks. Lossless and reversible; safe in every case.
Key abbreviation — replaces long, repeated keys with short aliases and emits a one-line legend you paste once. Big wins on arrays of records.
Full compact — whitespace stripping plus key abbreviation for the smallest possible payload.

Token counts use the standard ≈ 4-characters-per-token heuristic that closely tracks GPT and Claude tokenizers, so the before/after delta is a reliable guide to real savings.

Tips for prompt JSON

Always strip whitespace. Pretty-printing is for humans; the model does not need indentation to parse JSON.
Abbreviate only bulk data. For a 500-row table, short keys repeated 500 times save far more than the one-time legend costs.
Keep a legend in the system prompt. One line like t=title, p=price preserves meaning while keys stay tiny.
Re-check after edits. Adding fields can quietly re-inflate the payload — re-run before you ship a new version of the prompt.