Free Web Tools
Free tools from a working web studio
These are the tools our web production studio uses every day on real client projects. No signup, no cost. Each tool clearly explains how it processes data and whether anything is sent externally.
- Signup not required
- Price $0
- Data handling explained per tool
- AI-agent ready
-
Batch Image → WebP Converter Convert PNG/JPEG to WebP in bulk. Quality control and ZIP download. Works in Safari too. Drop images → adjust quality → save as ZIP
-
White Background Remover Automatically makes only the edge-connected white background transparent — white areas inside your artwork are kept. Drop an image → auto-processed → save PNG
-
WCAG Contrast Checker Calculates the WCAG 2.1 contrast ratio of text and background colors, with AA/AAA pass–fail results. Pick two colors → instant verdict → share via URL
-
Character Counter Characters, lines, full-/half-width counts, plus the real X (Twitter) weighted count (CJK=2, URL=23). Paste text → counted instantly
-
llms.txt Generator Build an llms.txt that tells LLMs and AI search engines what your site is about. A first step of GEO/LLMO. Fill in the form → generate → upload to root
-
JSON-LD Generator Generate Organization, FAQ, Service and Breadcrumb JSON-LD from a form. For rich results and AI search. Pick a type → fill in → paste into head
-
Markdown → PDF Turn Markdown into a clean A4 document and save as PDF. For proposals, quotes and specs. Tables supported. Paste Markdown → preview → save as PDF
-
OGP Meta Tag Wizard Three guided steps: preview the X / Facebook card and copy a full og: / twitter: tag set, with a required-item check. 3 steps → check cards → copy
-
Favicon Generator One image in — favicon.ico, apple-touch-icon, PWA icons and webmanifest out, with an HTML snippet. Drop an image → preview → save as ZIP
-
TikTok Publisher Post local videos to TikTok from a desktop browser, with privacy, interaction, and commercial-disclosure settings reviewed before posting. Connect TikTok → choose settings → post directly to TikTok
-
Encoding & Line Ending Converter Detect a CSV's encoding (Shift_JIS/UTF-8), BOM and line endings (CRLF/LF), then convert to UTF-8. For diagnosing garbled files. Drop a file → check detection → export
-
Batch Image → AVIF Converter Convert PNG/JPEG to AVIF in bulk and copy an AVIF-first <picture> snippet. Quality control and ZIP download. Drop images → convert → copy the snippet
-
Test Data Generator Dummy names, addresses, emails and phone numbers as CSV/JSON. Encoding and line endings, exact-length boundary strings, plus exact-byte-size files. Pick columns → set rows or size → copy or save
-
Marp Markdown → Slides Turn Markdown into Marp slides as you type. Japanese-friendly theme included, save as PDF via print, or download a self-contained HTML deck. Write Markdown → pick a theme → save as PDF or HTML
-
Text & Code Diff Checker Highlights additions, deletions and changes between two texts line by line and word by word. Inline or side-by-side view, and exports a unified diff (.patch). Paste both → read the diff → save the .patch
-
Cron Expression Explainer Reads a cron expression such as */15 * * * * back in plain English, breaks down every field and lists the upcoming run times. Time-zone aware. Paste the expression → read it back → check the dates
-
Base64 & Data URI Encoder Converts text to and from Base64, and turns a dropped image into a data:image/… URI with ready-made HTML img and CSS background-image snippets. SVG is percent-encoded to stay small. Paste text or drop an image → copy the snippet
-
URL Parameter Editor & UTM Builder Paste a URL to break its query string into an editable key/value table. Edit, add and remove parameters, add UTM tags, strip gclid and other click IDs, and encode or decode strings. Paste a URL → fix it → copy
-
HTML Entity Escape & Unescape Escape < > & " ' into HTML entities and decode & or ' back to characters. Named, decimal and hexadecimal references, double-escape detection and an entity cheat sheet. Paste → convert → copy
-
JSON ⇄ YAML Converter & Formatter Convert JSON and YAML either way as you type. Choose the indent width and quoting to reformat, see syntax errors by line and column, and get warnings for YAML traps like tab indents and 0755. Paste → convert → copy
-
PX ⇄ REM / EM Converter & Scale Convert px, rem and em against the root font size as you type. Copy the 12–64px scale as CSS variables or SCSS, or paste a stylesheet for a bulk px→rem pass that keeps hairlines and @media. Type → convert → copy
-
Color Converter & Alpha Calculator Convert HEX, RGB, HSL and OKLCH between each other, build rgba() / hsla() at any alpha, and see the composited colour over your background plus contrast ratios and an 11-step lightness palette. Enter → convert → copy
-
MD5 / SHA-256 / SHA-512 Hash Generator Hash any text or file with MD5, SHA-1, SHA-256, SHA-384 and SHA-512 at once. Paste a published checksum to verify it instantly, and copy the result as hex or Base64. Enter → hash → verify
-
JWT Decoder & Expiry Checker Paste a JWT to see its header and payload as formatted JSON with the time left before it expires on a bar. alg:none and milliseconds-instead-of-seconds are flagged, and a key verifies the signature. Paste → read → verify
-
User-Agent Parser & Device Detector Paste a UA string to break out the browser, version, engine, OS and device type. Every token is explained, and what the UA cannot tell you — frozen values, in-app browsers — is flagged. Paste → break down → check
-
UUID (v4) & ULID Bulk Generator Generate 1 to 100 UUID v4 or time-sortable ULID values at once. Write them out without hyphens, upper case or as a JSON array — and a batch stays in order even inside one millisecond. Pick → generate → copy
-
Aspect Ratio Calculator & Responsive Size Pick 16:9 or 4:3, type a width and the height appears. Work back from a size to a ratio, then copy the aspect-ratio CSS and a height table for every breakpoint. Pick → type → copy
-
Markdown Table Generator & CSV/TSV Converter Paste a range copied from a spreadsheet and get a clean Markdown table. Full-width characters count as two columns so the pipes line up, number columns are right-aligned, and you can export to CSV, TSV, HTML or JSON. Paste → choose → copy
-
SQL Query Formatter & Beautifier Paste a SELECT or JOIN query squashed onto one line and get uppercase keywords, a line break per clause and indented subqueries. Pick the indent width and comma position; UPDATE or DELETE without a WHERE gets flagged. Paste → choose → copy
-
QR Code Generator (SVG / PNG) Type a URL or a message and download the QR code as a print-sharp SVG or a PNG. Set the size, error correction level and quiet zone, and start from templates for Wi-Fi, email and more. Type → choose → save
-
Regex Tester (JavaScript) Type a pattern and some text to see every match highlighted, with capture groups, positions and a live replacement preview. Flip the flags, and get warned about a missing g or a ReDoS-shaped pattern. Write → paste → check
-
Unix Timestamp Converter Turn 1755999999 into a date and back again. Pick a time zone to see local time, UTC and a relative reading side by side, and paste a whole block of log lines to convert them all at once. Paste → choose → read
-
Memo & Checklist Quick notes and a simple checklist. Saved as you type, stored in your browser only, and exportable as Markdown. Try → install → write
-
Image Resizer & Cropper Shrink photos and screenshots in batches with a single instruction such as "long edge 1200px". Crop to 16:9 or a square from the centre, and write the result out as JPEG, PNG or WebP. Drop → set → save
-
EXIF Viewer & Remover List the date, camera model and GPS coordinates hidden inside a photo. Location data is flagged in red, and a clean copy is saved with the metadata stripped and the pixels untouched. Drop → inspect → strip
-
robots.txt Generator Write crawl rules and sitemap declarations from a form. For AI crawlers such as GPTBot, one preset turns away the training bots while keeping AI search. Choose → check → upload
-
Secure Password Generator Set the length, the character types and whether to drop look-alike characters, then mint up to 50 strong passwords at once. Strength is shown in bits and in time to crack. Choose → generate → copy
-
Case Converter Convert identifiers between camelCase, snake_case, kebab-case, PascalCase and CONSTANT_CASE. Batch-converts whole lists and tidies CSV header rows, splitting acronyms and digit runs the way you meant. Choose → paste → copy
For AI Agents
This site is designed to be used by AI agents as well as people. The contrast checker, character counter and OGP checker can be called directly via URL parameters, and the same logic is available as an MCP server for Claude and other AI tools. How to use from AI agents / llms.txt
Why Free
We build websites and provide AI consulting for small businesses in Japan. These tools are the ones we actually use for production and QA work, published as-is because they may help anyone facing the same tasks. For project inquiries, visit first-ch.com.