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Tools
18 free tools for developers, writers and everyday tasks — JSON, passwords, QR codes, converters and more.
Browse all 18 tools →
100% local • No server • No sign-up
Small tools.
Small tools.
Done instantly.
Free, bilingual utilities for developers, writers and everyday tasks. Everything runs in your browser — your text never leaves your device.
Built for ohmyrika.tech • 中英双语 • 免费使用，无需注册
Why people bookmark this
Fast, private, and works on phone & desktop. No uploads, no tracking of your input.
18Tools live
0Server uploads
8Languages
∞Free forever
Explore ohmyrika.tech
Start with the tools — more sections will live here as the site grows.
✏️
Blog
Notes, tutorials and updates. This section hasn't launched yet.
Coming soon👋
About
Who built this, how to get in touch, and the privacy & terms for the site.
About & contact →How it works
Pick a tool, paste or type, get the result instantly. Instructions and FAQs are on every tool page.
🔒 Private by design
All formatting, generating and encoding happens with JavaScript in your browser. Close the tab and your data is gone.
⚡ Made for repeat use
Clean, mobile-friendly pages with copy & download buttons, so daily tasks take seconds — not minutes.
ohmyrika.tech/tools
All tools
Search or filter by category. All 18 tools run locally in your browser.
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JSON Formatter & Validator
Beautify, validate & minify JSON with clear error messages.
Open tool →🔑
Password Generator
Strong random passwords, generated locally with Web Crypto.
Open tool →✍️
Word & Character Counter
Words, characters, sentences & reading time — live.
Open tool →⇄
Base64 / URL Encoder-Decoder
UTF-8 safe Base64 and URL encoding & decoding.
Open tool →▦
QR Code Tool
Generate QR codes or scan them — camera & image, all local.
Open tool →🆔
UUID Generator
Bulk-generate random UUID v4 values.
Open tool →🕐
Timestamp Converter
Unix seconds / ms ↔ human date, with live clock.
Open tool →/.*/
Regex Tester
Test patterns live with highlighted matches.
Open tool →⏱
Cron Builder
Build cron expressions from presets & plain words.
Open tool →⇄
CSV ↔ JSON Converter
CSV to JSON array and back, in your browser.
Open tool →Aa
Case Converter
UPPER, lower, Title, camel, snake, kebab & more.
Open tool →¶
Lorem Ipsum Generator
Placeholder paragraphs, sentences or words.
Open tool →M↓
Markdown Preview
Live Markdown editor with rendered preview.
Open tool →🎨
Color Picker & Converter
Pick colors, copy HEX / RGB / HSL instantly.
Open tool →🗜
Image Compressor
Compress images locally — never uploaded.
Open tool →✦
AI Prompt Builder
Role + task + context + format, ready to paste.
Open tool →±
Text Diff Checker
Compare two texts line by line with highlights.
Open tool →📐
Unit Converter
Length, weight, temperature & data size.
Open tool →JSON Formatter & Validator
JSON Formatter & Validator
Format, validate, minify and inspect JSON instantly.
Ready
How to use
- Paste JSON into the left box.
- Click Format to pretty-print, Validate to check, or Minify to compress.
- Copy the result. Errors show the reason from the parser.
Is my JSON sent to a server?
No. Parsing uses JSON.parse in your browser only.
Why is my JSON invalid?
Common causes: trailing commas, single quotes, unquoted keys, or missing brackets. The error message points to the issue.
Can I format large JSON?
Yes, for typical API responses. Very large files (10MB+) may be slow on low-end phones.
Password Generator
Password Generator
Create strong, random passwords with crypto-grade randomness.
Strength: —
Generated locally with crypto.getRandomValues. We never store or send your passwords.
How to use
- Choose length (16+ recommended) and character sets.
- Click Generate, then Copy.
- Save it in a password manager — don't reuse it elsewhere.
How long should a password be?
At least 16 characters for important accounts. Length matters more than complexity tricks.
Is this generator safe?
It uses the Web Crypto API in your browser and generates on your device. Still, use a trusted password manager for storage.
Word & Character Counter
Word & Character Counter
Count words, characters, sentences and reading time — live as you type. Works for English & Chinese.
0Characters
0No spaces
0Words
0Sentences
0Paragraphs
0Lines
0sReading time
0sSpeaking time
How to use
Type or paste text — counts update instantly. Chinese characters are counted as characters; word count splits on spaces and punctuation for mixed text.
How is reading time calculated?
About 200 words per minute for English and ~400 characters per minute for Chinese, blended for mixed text. It's an estimate.
Does it count Chinese words accurately?
Character count is exact. Word segmentation for Chinese without spaces is approximate — use character count for limits (e.g., Xiaohongshu / Weibo).
Base64 / URL Encoder-Decoder
Base64 / URL Encoder-Decoder
Encode and decode Base64 and URL components with full UTF-8 (Chinese) support.
How to use
Pick a mode, enter text, click Convert. Base64 here is UTF-8 safe, so Chinese, emoji and accents round-trip correctly.
Base64 vs URL encoding?
Base64 turns binary/text into ASCII for transport. URL encoding escapes characters that aren't allowed in URLs (like spaces and Chinese).
Why did decode fail?
The input isn't valid for that mode — e.g., invalid Base64 characters or a malformed % escape in a URL.
QR Code Tool
QR Code Tool
Generate a QR code from any link or text — or scan one with your camera or an image. Two tabs, one tool, all local.
Tip: Test-scan the code before printing or sharing.
QR preview
How to use
- Enter a URL or any text.
- Choose a size (larger for print).
- Generate, then download the PNG.
Do QR codes expire?
No. These are static QR codes — they encode your text directly and never expire, as long as the linked page stays live.
What's the max content?
Roughly 2,000+ characters, but shorter is more reliable to scan. Use a short URL for links.
UUID Generator
UUID Generator
Generate random UUID v4 values in bulk.
How to use
Pick how many you need and click Generate. Uses crypto.randomUUID / getRandomValues locally — collisions are practically impossible for v4.
Timestamp Converter
Timestamp Converter
Convert between Unix timestamps (seconds / milliseconds) and human dates.
Now:
How to use
10-digit values are treated as seconds, 13-digit as milliseconds. Dates use your device timezone; UTC is shown too.
Regex Tester
Regex Tester
Test regular expressions live and see every match highlighted.
Matches: 0
How to use
Enter a pattern and flags (g, i, m, s, u), then your test text. Matches are highlighted and counted. Invalid patterns show the error.
Cron Expression Builder
Cron Expression Builder
Build a 5-field cron expression from simple choices and read it in plain words.
Fields: minute · hour · day of month · month · day of week (0 = Sunday)
CSV ↔ JSON Converter
CSV ↔ JSON Converter
Convert CSV to a JSON array, or a JSON array of objects back to CSV.
How to use
CSV → JSON uses the first row as headers and supports quoted fields with commas. JSON → CSV expects an array of flat objects.
Case Converter
Case Converter
UPPER, lower, Title, camelCase, snake_case, kebab-case and more.
Lorem Ipsum Generator
Lorem Ipsum Generator
Placeholder paragraphs, sentences or words for mockups and layouts.
Markdown Preview
Markdown Preview
Write Markdown on the left, see rendered HTML live on the right.
Color Picker & Converter
Color Picker & HEX / RGB / HSL Converter
Pick a color and copy HEX, RGB and HSL values instantly.
#0F766EHEX
rgb(15,118,110)RGB
hsl(175,77%,26%)HSL
Image Compressor
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Image Compressor
Compress JPG / PNG / WebP in your browser. Your images are never uploaded.
Tap to choose an image
Before
After
AI Prompt Builder
AI Prompt Builder
Assemble a structured prompt — role, task, context, format — ready to paste into any AI chat.
Text Diff Checker
Text Diff Checker
Compare two texts line by line — added and removed lines are highlighted.
Unit Converter
Unit Converter
Length, weight, temperature and data size — converted instantly.
About OhMyRika Tools
OhMyRika Tools (ohmyrika.tech) is a small, independent collection of free web utilities built to be fast, private and bilingual. No accounts, no uploads — tools run entirely in your browser.
We started with the five tools people reach for every day: JSON formatting, password generation, word counting, Base64/URL encoding, and QR codes. More tools will be added based on what visitors actually need.
Contact: [email protected]
Contact
Questions, bug reports or tool suggestions? Email us — we read everything.
For faster help, include the tool name, what you entered (without sensitive data), and what went wrong.
Privacy Policy
Last updated: 2026-10-19
Your tool inputs are processed locally in your browser and are not sent to, stored on, or logged by our servers — there is no server for these tools.
We may use privacy-friendly analytics and advertising (e.g., Google AdSense) in the future, which may use cookies as described by those providers. You can block cookies in your browser settings.
If you email us, we use your address only to reply. Questions: [email protected]
Terms of Use
Last updated: 2026-10-19
These tools are provided free of charge, "as is", without warranties. Verify important results (especially passwords, encoded data and QR codes) before relying on them.
You are responsible for how you use the outputs. Don't use the tools for unlawful purposes. We may update or discontinue tools at any time.