devsimpletools

Converters, encoders, formatters and LLM utilities. Free, no sign-up and 100% in your browser: your content is never uploaded.

AI / LLM

Token Counter — Count tokens and estimate prompt cost.
LLM JSON Repair — Rescue the JSON a model returns.
JSONL Validator — Validate JSONL line by line and pinpoint the bad one.
Chat Payload Viewer — Read a messages payload as a conversation.
SSE Stream Viewer — Reassemble a streaming response.

Converters

JSON ↔ YAML — Convert objects between JSON and YAML notation.
CSV ↔ JSON — Turn CSV rows into arrays of JSON objects and back.
Query String ↔ JSON — Turn URL parameters into flat JSON objects.
Number Base Converter — Convert numbers between binary, octal, decimal and hexadecimal.

Encoders / Decoders

URL Encoder/Decoder — Encode and decode URL components.
Base64 Encoder/Decoder — Encode and decode text in Base64.
HTML Entity Encoder/Decoder — Escape and unescape HTML entities.
JWT Decoder — Break a JWT into header, payload and signature.

Generators

UUID/GUID Generator — Generate v4 unique identifiers.
Password/Token Generator — Generate secure random passwords and tokens.
Hash Generator — Compute MD5, SHA-1, SHA-256 and SHA-512 hashes.
Lorem Ipsum Generator — Generate filler paragraphs, sentences or words.

Formatters

JSON Formatter/Validator — Validate, format and minify JSON.
SQL Formatter — Apply consistent indentation and casing to SQL queries.
Markdown Previewer — Render Markdown to HTML live.
XML Formatter — Format and validate XML documents.

Text

Case Converter — Convert text between camelCase, snake_case, kebab-case and more.
Text Diff Checker — Compare two texts and highlight line-by-line differences.
Regex Tester — Test regular expressions against sample text.
Slug Generator — Turn titles into URL slugs.

Time

Timestamp Converter — Convert between Unix timestamps and readable dates.
Cron Expression Parser/Explainer — Explain in plain language what a cron expression does.

Design

Color Converter — Convert colours between HEX, RGB and HSL.