Fast. Private. Browser-only.

Developer tools that run entirely in your browser.

Format, validate, decode and convert developer data instantly. No accounts, no uploads, no backend processing.

Instant

No round trips or waiting for an API.

Private

Tokens and payloads stay on this device.

Installable

Use ElDevo as a lightweight PWA.

Developer toolkit

Find the right tool quickly

Encoding

Base64 Encoder / Decoder

UTF-8 safe Base64 encoding and decoding with optional URL-safe alphabet. Everything happens locally.

Utilities

Cron Expression Generator

Build cron schedules interactively, translate them to plain English and preview the next five run times locally.

Converters

CSV to JSON Converter

Parse CSV or TSV data with Papa Parse and export a clean JSON array locally.

Security

Hash Generator

Calculate SHA-1, SHA-256, SHA-384 and SHA-512 hashes with the browser Web Crypto API.

Encoding

HTML Entity Encoder / Decoder

Encode special characters such as &, < and > into HTML entities, or decode entities back to readable text.

Web

HTML Formatter

Beautify HTML documents locally with readable indentation and browser-native parsing.

JSON

JSON Formatter & Validator

Fast browser-based JSON formatter and validator with precise syntax errors. Your JSON never leaves this device.

JSON

JSON Path Tester

Explore JSON data with a lightweight client-side JSONPath-style query tool supporting dot paths and array indexes.

JSON

JSON Schema Validator

Validate a JSON document against a practical subset of JSON Schema locally, including types, required properties, arrays and enums.

Converters

JSON to TypeScript Converter

Turn JSON examples into readable TypeScript interfaces locally, including nested objects and arrays.

Converters

JSON to YAML Converter

Convert JSON to readable YAML using js-yaml entirely in your browser.

Security

JWT Decoder

Decode JSON Web Tokens entirely in your browser. Inspect header, payload, expiration and signature status without verification or server uploads.

Browse all tools

100% Client-Side. Your data is processed locally and is never sent to an ElDevo processing server.

ElDevo is a privacy-first hub for small developer tasks. Parsers, encoders, formatters and converters execute in the browser so sensitive tokens, source snippets and data files do not need to leave your machine.