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Rashid Salimov
Rashid Salimov

Posted on Originally published at vault-pro.rashid-salimov96.workers.dev

Show DEV: I Built 90+ Free Client-Side Developer Tools (Zero Uploads, 100% In-Browser)

#webdev #programming #showdev #opensource

Have you ever paused before clicking "Format" or "Convert" on a random web tool, wondering: Where does my clipboard content actually go?

As developers, we constantly need quick utilities:

  • Decoding a production JWT to check expiration timestamps
  • Converting a curl command with an active Authorization: Bearer token into Python or Node.js fetch code
  • Formatting an unreadable JSON payload containing real customer records
  • Calculating a complex POSIX cron schedule
  • Merging two sensitive PDF contracts or signing a tax document

The dirty secret of most online utility portals (TinyWow, Smallpdf, random converters ranking #1 on Google) is that they upload your files and strings to their backend servers. Even if they claim to delete files after 1 hour, your internal tokens, database structures, and employee records sit in their server memory, access logs, and temp disks.

To put an end to this, I built Digital Vault PRO ā€” a suite of 90+ fast, free online utilities running 100% locally inside your browser.

šŸ”’ The Zero-Upload Architecture

Digital Vault PRO is engineered with a strict principle: Your files and data must never leave your machine.

Here is the technical stack that makes it possible:

  1. Astro 5 SSG on Cloudflare Workers Static Assets: The site compiles to pure static HTML, CSS, and vanilla TypeScript. Pages load in under 50ms from edge locations worldwide with zero client-side layout shift (CLS: 0.00).
  2. WebAssembly (WASM): Heavy operations (such as multi-page PDF assembling, image quantization, and cryptographic hashes) run in sandboxed WASM threads inside your browser.
  3. Native Web Crypto API: Cryptographic operations (UUID v4 generation, SHA-256 / SHA-512 hashing, AES encryption) use the browser's hardware-accelerated crypto.subtle API.
  4. Zero Outbound Telemetry: You can open your browser's DevTools Network tab right now, drop a 50MB image or a 10,000-line JSON file, and observe 0 outbound network requests.

šŸ› ļø 10 Daily Developer Tools You Can Use Right Now

Here are 10 of the most popular tools available without sign-up or paywalls:

1. cURL to Code Converter

Paste any complex cURL command (with headers, multipart form data, basic auth, or bearer tokens) and instantly get idiomatic, copy-pasteable code for JavaScript (fetch & axios), Python (requests), Go, PHP, Rust, and Node.js.

2. JSON to TypeScript Interface Generator

Drop any raw JSON API response. The tool analyzes deep nested objects, arrays, and optional keys, generating clean, type-safe TypeScript interfaces with optional fields and exported types.

3. Visual Cron Schedule Builder & Human Explainer

Tired of debugging whether 0 0 * * 1 runs on Sunday or Monday? This tool translates any 5-part POSIX cron expression into plain English, lists the exact next 5 execution timestamps, and provides quick presets (every 5 minutes, weekdays at 9am, weekly).

4. JWT Decoder & Header Inspector

Inspect JWT Header and Payload JSON structures, decode base64url encoding, check expiration (exp), issued-at (iat), and signature algorithms locally. Your production tokens never touch a remote server.

5. Linux Chmod Permission Calculator

Visual matrix for Owner, Group, and Others with Read (4), Write (2), and Execute (1) flags. Generates exact octal codes (755, 644, 600, 400) and the exact CLI command (chmod 600 id_rsa).

6. Regex Pattern Tester & Match Debugger

Test regular expressions in real-time with syntax highlighting, capture group extraction, global/multiline flags, and built-in presets (email, URL, UUID, IPv4, IPv6, semantic versioning).

7. Client-Side Image Compressor & WebP Converter

Compress JPEG, PNG, and WebP assets right inside an HTML5 Canvas context. Set max dimensions, target file size, and quality slider. Perfect for optimizing assets before committing to Git.

8. PDF Merger & Page Organizer

Merge dozens of PDF documents into a single document entirely via pdf-lib in the browser. Zero cloud upload.

9. CIDR Subnet Calculator

Calculate IPv4 network ranges, subnet masks, wildcard masks, usable host IP ranges, and broadcast addresses for cloud VPCs (AWS, GCP, Hetzner, Cloudflare).

10. Secure Password & Cryptographic Token Generator

Generate cryptographically random passwords, API keys, and secrets using crypto.getRandomValues(). Includes entropy calculation (in bits) and zero server storage.

šŸ·ļø Free Badge for Your GitHub READMEs

If you care about client-side privacy or want to show your project runs offline, we also host a zero-dependency SVG badge API:

[![Digital Vault](https://vault-pro.rashid-salimov96.workers.dev/api/badge?label=Tools&status=Client-Side&color=10b981)](https://vault-pro.rashid-salimov96.workers.dev/)
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Renders dynamically as:
Tools | Client-Side with 24-hour edge caching.

šŸ’” What's Next?

Digital Vault PRO is completely free, supports dark and light modes, and is available in English and Russian. It also runs inside a Telegram Mini App if you prefer using it on mobile.

šŸ‘‰ Check it out live: https://vault-pro.rashid-salimov96.workers.dev/en/

Iā€™d love your feedback:

  • What client-side utility do you find yourself needing most often?
  • Any specific edge cases or tools you'd like added to the suite?

Drop your thoughts and roast my architecture below! šŸš€

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