Browser-based developer utilities

Small tools for everyday debugging.

Format, decode, inspect and transform data without sending it to a server.

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Private by default. Everything runs in your browser.

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AI tools

Token / Character CounterEstimate tokens and inspect text size. OpenAI Message FormatterTurn chat messages into valid API JSON. LLM API Request BuilderBuild an OpenAI-compatible request body. Embedding Text Chunk CalculatorEstimate chunks from text length and overlap. Text ChunkerSplit text into retrieval-friendly chunks. Cosine Similarity CalculatorCompare two embedding vectors.

JSON

JSON FormatterFormat, validate and minify JSON. JSON ValidatorCheck JSON syntax instantly.

Encoding & decoding

Base64 Encoder / DecoderConvert text to and from Base64. URL Encoder / DecoderSafely encode URL components. JWT DecoderInspect JWT header and payload.

Text & developer utilities

Regex TesterTest patterns with live match highlighting. Password GeneratorCreate strong random passwords. Cron Expression GeneratorBuild a readable cron expression. UUID GeneratorGenerate standards-based UUIDs. Case ConverterSwitch text between upper and lower case. Word & Character CounterCount words, characters and lines. Timestamp GeneratorConvert Unix timestamps and dates. Remove Duplicate LinesClean repeated lines from text. Sort LinesSort multiline text alphabetically. URL ParserInspect URL parts and query parameters.

Fast, focused, and private

DevToolLine keeps common development utilities close at hand. No account is required and tool inputs stay on your device.