Free browser tools that respect your data
Every tool on this site runs locally in your browser. Nothing you paste is uploaded, logged or stored.
Developer tools
Format, convert, encode and inspect data without leaving the browser.
JSON Formatter & Validator
Pretty-print, minify, sort keys and pinpoint syntax errors by line and column.
JSON ↔ YAML Converter
Convert between JSON and YAML in both directions, with validation.
JSON ↔ CSV Converter
Turn arrays of objects into CSV and CSV back into JSON, with header and delimiter options.
XML Formatter
Beautify or minify XML and report parse errors.
SQL Formatter
Format SQL for MySQL, PostgreSQL, SQLite and more with consistent indentation and keyword case.
Regex Tester
Test JavaScript regular expressions live with match highlighting and capture groups.
Text Diff
Compare two texts line by line or word by word and see additions and deletions.
Markdown Preview
Write Markdown and see sanitized HTML side by side; copy the HTML.
Base64 Encoder / Decoder
Encode and decode text or files as Base64, UTF-8 safe, with data URL output.
URL Encoder & Parser
Encode or decode URL components and break a URL into its parts and query parameters.
JWT Decoder
Decode JSON Web Tokens, read claims and expiry, and verify HS256 signatures locally.
UUID / ULID Generator
Generate UUID v4, time-ordered UUID v7 and ULID identifiers in bulk.
Hash Generator
Compute MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of text or files.
Cron Expression Parser
Explain a cron expression in plain language and list its next run times.
Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates in any time zone.
Case Converter
Switch text between camelCase, snake_case, kebab-case, PascalCase, Title Case and more.
Number Base Converter
Convert between binary, octal, decimal, hexadecimal and any base from 2 to 36, with big numbers.
Password Generator
Generate strong random passwords and passphrases with an entropy estimate.
Chmod Calculator
Convert Unix file permissions between checkboxes, octal (755) and symbolic (rwxr-xr-x).
IP Subnet / CIDR Calculator
Get network, broadcast, host range, mask and wildcard for any IPv4 CIDR block.
Taiwan life & finance
Calculators and checkers for everyday life in Taiwan: salary, tax, insurance, IDs and dates.
Taiwan ID Number Validator
Check a Taiwan national ID or resident certificate number, see its region and gender code, or generate test numbers.
Taiwan Business Number Validator
Validate an 8-digit Taiwan unified business number (統一編號) using the current checksum rules.
Uniform Invoice Lottery Checker
Check your receipt numbers against the current period's winning numbers.
Lunar ↔ Solar Calendar Converter
Convert between the Gregorian and Chinese lunar calendars, with zodiac, stems-and-branches and solar terms.
ROC Year Converter & Age Calculator
Convert between ROC (民國) and Western years and compute exact age from a birth date.
Chinese Numeral Amount Converter
Turn numbers into formal Chinese numerals (壹貳參…) for cheques, contracts and receipts.
Labor & Health Insurance Calculator
Estimate monthly labor insurance, health insurance and pension contributions for employee and employer.
Taiwan Income Tax Estimator
Estimate individual income tax from salary, exemptions and deductions using the current brackets.
Overtime Pay Calculator
Compute hourly wage and overtime pay under the Labor Standards Act, including rest days and holidays.
Mortgage Calculator
Monthly payments and a full amortization schedule, with grace period and equal-principal options.
Compound Interest Calculator
Project savings or investments with compound interest and regular contributions.
Date Calculator
Days between dates, add or subtract days, and count working days.
Unit Converter
Length, area, weight, volume and temperature, including Taiwan units like 坪, 台斤 and 甲.
Percentage Calculator
What is X% of Y, percentage change, and what percent X is of Y.
BMI Calculator
Body mass index with the Taiwan Ministry of Health and Welfare weight categories.
Bill Splitter
Split a bill evenly or by item, with optional service charge and tip.
Electricity Bill Estimator
Estimate a Taipower residential bill from kWh using the tiered summer and non-summer rates.
Fuel Cost Calculator
Trip fuel cost from distance, consumption and price; convert km/L and L/100 km.
Taiwan Bank Code Lookup
Find the 3-digit bank code for transfers by bank name or code.
Discount Calculator
Final price after a discount (Taiwan-style 打折 included), savings, and unit-price comparison.
Why this site exists
Most online utilities send your data to a server you know nothing about. These tools do the work on your device instead, so you can use them with sensitive data without a second thought.