27 Best Free Developer Tools Online in 2026
Browser-based utilities every developer needs — JSON viewer, regex tester, diff checker, QR generator, Base64 encoder, CSS gradients, fake data, code screenshots and more. No installation, no signup, no file uploads. All processing happens locally in your browser.
27 dev tools
all completely free
No install
runs in your browser
No signup
open and use instantly
Works offline
after first page load
All 27 Free Developer Tools
JSON Preview
Visualize JSON as a collapsible, searchable interactive tree. Faster than browser devtools.
Regex Tester
Test regex patterns in real time with match highlights, groups & a built-in cheat sheet.
Diff Checker
Compare text, JSON or images side by side. Line-by-line diff with highlights.
Code Screenshot
Create beautiful, syntax-highlighted code snippet images for sharing and presentations.
Base64 Encode / Decode
Encode and decode Base64, URL encoding and HTML entities — instant, no limits.
QR Code Generator
Generate QR codes for URLs, WiFi credentials, vCards and plain text. Download as PNG or SVG.
JSON ↔ CSV Converter
Convert JSON to CSV and back. Choose delimiter, handle nested objects, download instantly.
Password Generator
Generate crypto-secure passwords with custom rules. Bulk generate hundreds at once.
Color Picker & Palette
Pick colors in Hex, RGB and HSL. Check WCAG contrast ratios for accessibility.
Markdown Studio
Write and preview Markdown with live rendering. Export to HTML or PDF.
Fake Data Generator
Generate realistic mock data — names, emails, addresses, credit cards. Download as CSV or JSON.
API Formatter
Paste any API response to inspect headers, status code and beautify the JSON body.
Barcode Generator
Generate Code128, EAN-13, UPC-A, ITF and more barcodes. Download as SVG or PNG.
Email Signature Generator
Create professional HTML email signatures for Gmail, Outlook and Apple Mail. Copy in one click.
SVG Optimizer
Clean and reduce SVG file size using SVGO. Paste Figma or Illustrator SVGs and compress.
Favicon Generator
Create ICO, PNG and web manifest icons from any image. Generates all sizes at once.
Word Counter
Count words, characters, sentences and estimate reading time. Keyword density for SEO.
CSS Gradient Generator
Build linear, radial and conic CSS gradients visually. Copy the CSS in one click.
Lorem Ipsum Generator
Generate placeholder paragraphs, sentences or words. Choose language and count.
Multi-Format Converter
Convert files to Text, Table, JSON and Images all at once. One upload, multiple outputs.
CSV Visual Debugger
Find duplicate rows, empty cells and column inconsistencies in CSV files visually.
Bulk File Renamer
Rename files using date, numbering and pattern rules. Process entire folders at once.
Folder Structure Visualizer
Generate an interactive tree view of your project structure. Detects unused files.
Resume Builder
Build ATS-optimized resumes with 20+ templates. Live preview, PDF export, auto-save.
Word to PDF
Convert DOCX Word documents to PDF entirely in your browser. No upload, no LibreOffice needed.
JSON to PPTX
Generate PowerPoint presentations from JSON data. Automate slide decks from any data source.
JS to PPTX
Write JavaScript to generate PowerPoint decks programmatically. Full pptxgenjs API.
Toolsz vs JSONCrack vs Carbon vs Regex101
Most dev tools cover one use case. Toolsz covers 25.
| Feature | Toolsz ✓ | JSONCrack | Carbon | Regex101 |
|---|---|---|---|---|
| Price | Free forever | Free (limited) | Free | Free |
| File uploads | None — browser | Server | Server | None |
| Signup required | No | Yes (Pro) | No | No |
| Tool variety | 27 tools | 1 tool | 1 tool | 1 tool |
| JSON + Regex + QR | ✓ All in one | JSON only | Code only | Regex only |
| Offline capable | ✓ Yes | No | No | No |
| Diff checker | ✓ Free | ✗ | ✗ | ✗ |
| Fake data gen | ✓ Free | ✗ | ✗ | ✗ |
| Privacy | 100% local | Server process | Server | Local |
Frequently Asked Questions
The best free browser-based developer tools in 2026 include Toolsz (27 tools including JSON viewer, regex tester, diff checker, code screenshot, QR generator, Base64 encoder, resume builder, Word to PDF, and more), Regex101 (regex testing), JSONCrack (JSON visualization), Carbon (code screenshots) and CyberChef (encoding). Toolsz stands out by combining all of these in one place with no signup or file uploads.
Yes. Toolsz's JSON Preview tool visualizes JSON as an interactive, collapsible tree with syntax highlighting. You can search within the JSON, expand or collapse nodes, and copy values. It's faster than browser devtools and works entirely in your browser without uploading your data.
Toolsz's Regex Tester provides real-time pattern matching with group highlights and a built-in cheat sheet. It supports JavaScript regex syntax. For more advanced regex features like PCRE support and unit tests, Regex101.com is the gold standard. Both are free and require no signup.
Use Toolsz's QR Code Generator. It generates QR codes for URLs, WiFi passwords, vCards, email addresses and plain text. Download as PNG or SVG. No signup, no watermarks, no limits — and it works entirely offline after the first page load.
Toolsz's Base64 tool encodes and decodes Base64, URL encoding and HTML entities. It handles large strings, shows character counts and copies to clipboard instantly. It runs locally — your data is never sent to any server, which is important when encoding sensitive credentials or API keys.
Use the Fake Data Generator on Toolsz. It generates realistic mock data including names, emails, phone numbers, addresses, company names, credit card numbers and more. You can generate hundreds of rows and download as CSV or JSON for use in testing.
Yes. Once a Toolsz page has loaded in your browser, most tools work without an internet connection because all processing happens locally using JavaScript. This is ideal for developers in environments with restricted internet access or when working with sensitive data.