Text Tools
Character count, full-width/half-width conversion, text diff comparison, and more — handle everyday text processing right in the browser. No sign-up required.
Text Tool List
Character Counter
Count characters, words, lines, and bytes in real time. Great for social media posts and reports.
Fullwidth / Halfwidth Converter
Convert between fullwidth and halfwidth characters. Also supports katakana-hiragana conversion for data cleanup.
JSON Formatter & Validator
Pretty-print or minify JSON data. Catch syntax errors instantly with line numbers and tree view.
Text Diff Checker
Compare two texts side by side and highlight every difference. Character-level detection with merge support.
Japanese Era Converter
Convert between Western calendar years and Japanese era names (Reiwa, Heisei, Showa). Includes age calculator.
Password Generator
Generate strong, random passwords instantly. Customize length, character types, and check strength.
🔒 sakutto tools run entirely in your browser by default
Your files are generally never uploaded to a server. A few tools require external communication due to CORS constraints or third-party APIs. View Privacy Policy
Free online text tools — count, convert, format, and compare
The sakutto Text category bundles every common text utility you need day-to-day: character counting, full-width/half-width conversion, JSON formatting, text diff comparison, Japanese era (wareki) conversion, and password generation. Every tool is free, requires no sign-up, and runs entirely in your browser, so manuscripts, source code, and passwords stay on your device.
Count characters and convert width with text utilities
character-counter measures characters, lines, byte length, and full-width/half-width breakdown in real time. fullwidth-halfwidth converts between the two widths. Useful for Twitter/X 140-character limits, report length requirements, and form field validation.
Format JSON and diff text content
json-formatter pretty-prints and validates JSON data; diff highlights the difference between two text inputs. Perfect for inspecting API responses, code reviews, and tracking revisions in documents and contracts.
Convert Japanese era (wareki) and generate passwords
era-converter switches between the Japanese imperial era (Reiwa, Heisei, Showa) and the Gregorian calendar. password-generator creates strong random passwords with configurable length and character sets. Both speed up everyday paperwork and account setup.
How to use the character counter and full-width/half-width tools
When you need to manage character counts strictly — for manuscripts, SNS posts, or report submissions — character-counter handles the job in seconds.
Paste text into the input area
Open character-counter and paste the text you want to measure into the textarea. The counts for characters, lines, byte length, and full-width/half-width are updated in real time as you type or paste.
Pick a counting rule for accurate results
Choose the counting mode that matches your use case: Twitter/X 140-character rule, Microsoft Word definition, or half-width=1/full-width=2 byte conversion. It covers report length requirements, product description limits, and SEO title 32-character checks.
Format, compare, and diff text content
Make data easier to read, spot the differences between two versions, and review code or documents — all with sakutto's text formatting and diff tools.
- Format JSON for readability (json-formatter)
- json-formatter pretty-prints API responses and config files with proper indentation. It detects syntax errors, visualizes nested structures, and can also unminify minified JSON. An everyday tool for engineers, data analysts, and API debugging.
- Visually compare two texts (diff)
- The diff tool shows two pieces of text side by side with color-coded differences. Use it for document revisions, code version comparisons, email proofreading, and contract change tracking. Both line-level and word-level diffing are supported.
Era conversion, password generation, and other practical text tools
These are the small but essential utilities you reach for during paperwork or daily work — designed to be as quick as a calculator.
- Convert Japanese era and Gregorian dates (era-converter)
- era-converter handles bidirectional conversion between Japanese eras (Reiwa, Heisei, Showa, Taisho, Meiji) and the Gregorian calendar. It is invaluable for government paperwork, contracts, resumes, and medical records that require wareki notation. Precise to the day.
- Generate strong random passwords (password-generator)
- password-generator creates random passwords using letters, numbers, and symbols. You can configure length, symbol inclusion, and character mixing. Use it for fresh entries in your password manager or for safe sign-ups to new services.
- Generated locally so the password never leaks
- password-generator runs entirely in your browser, so generated strings are never transmitted to a server. The whole flow — generate, copy, use — stays local and safe.
Why text data is safe to process entirely in your browser
Manuscripts, passwords, and JSON often carry sensitive information. sakutto's text tools run entirely in the browser, so you can use them without worry.
- All text processing is client-side
- character-counter, fullwidth-halfwidth, json-formatter, diff, era-converter, and password-generator all process text inside your browser. The text you type or paste is never transmitted to a server.
- Free, no sign-up, no character limit
- Text tools are free with no sign-up and no character limit. Because text is small compared with files, the Free plan handles long passages and large datasets without any practical restriction.
Text — Frequently Asked Questions
Are sakutto's text tools really free? Do I need to sign up?
Yes, every text tool on sakutto — character counter, full-width/half-width converter, JSON formatter, text diff, era converter, and password generator — is free and requires no sign-up. There is no character limit, and the Free plan handles long passages and large datasets just fine.
Is my text data uploaded to a server?
No. sakutto's text tools all run entirely client-side in your browser, so the text you type or paste is never transmitted to a server. That makes them safe for manuscripts, passwords, API responses, and contracts. They keep working even when you're offline.
Does the character counter support Twitter/X 140-character counting?
Yes — character-counter supports Twitter/X 140-character counting and several other rules (such as half-width=1/full-width=2 byte mode). Paste text and it shows characters, lines, and byte counts in real time. It also helps with SNS posts, report length checks, and SEO title 32-character limits.
Can I customize indentation when formatting JSON?
json-formatter lets you choose indentation width (2-space, 4-space, or tab) and supports both pretty-printing and minification. When the JSON contains a syntax error, the position is reported so you can debug API responses quickly.
Are the passwords generated by sakutto stored anywhere?
password-generator runs entirely in your browser, so generated strings are never transmitted or stored anywhere on our servers. Copy the generated password and store it in your own password manager or other secure location.
Text Articles
All articlesJapanese Era Notation Rules for Business Documents | Wareki vs. Western Calendar
Learn when to use Japan's traditional era calendar (wareki) versus the Western calendar (seireki) in business documents. A guide covering contracts, invoices, resumes, and more.
How to Calculate Your Age from Birth Year | Japanese Era & Western Calendar Reference Table
Learn how to calculate age from a birth year in Japan's wareki or Western calendar. Includes a 2026 age reference table for Reiwa, Heisei, and Showa, plus school enrollment and graduation years.
Japanese Era Names Explained: Reiwa, Heisei, Showa, Taisho, Meiji — Complete Timeline
A complete overview of Japan's five modern era names — Reiwa, Heisei, Showa, Taisho, and Meiji. Covers dates, durations, historical events, and easy conversion formulas.
Reiwa to Western Year Conversion Table [2019–2030]
A quick-reference table for converting between Japan's Reiwa era and Western calendar years. Covers Reiwa Gannen (2019) through Reiwa 12 (2030), with an easy formula and common lookups.
Best Japanese Era Converter Tools Compared (2026) | Free Options
A comparison of free Japanese era conversion tools (wareki ↔ seireki). Covers features, usability, and supported date ranges to help you choose the right tool for your needs.
Japanese Era ↔ Western Year Quick-Reference Table [2026 Edition]
A complete quick-reference table for converting between Japan's wareki (era calendar) and Western years. Covers Reiwa, Heisei, Showa, Taisho, and Meiji with ages as of 2026. Perfect for resumes and official documents.