20 Free Developer Tools We Built (And Why We Gave Them Away)
We built 20 utility tools and made them completely free. No signup, no ads, no catch. Here's the full list and why we did it.
Jo4 Blog
Insights on URL shortening, link management, and web development from the Jo4 team.
The Easiest Integration We've Ever Done: Two Markdown Files and a Domain Name Identity Crisis
ClawHub integration took 30 minutes. The hardest part? Keeping up with their domain name changes. From calwd to openclaw to clawhub - we've seen it all.
Getting Your App on Pipedream: No Dashboard, Just Humans (And That's Actually Great)
Pipedream doesn't have a developer dashboard. You email their team directly. Sounds scary? It's actually the fastest integration process we've experienced.
The 5 Edge Cases That Broke Our Dev.to Auto-Crossposting (And How We Fixed Them)
Auto-crossposting sounds simple until you deal with duplicates, stale dates, and race conditions. Here's how we made it bulletproof.
5 Hard Lessons from Implementing Zapier OAuth in Spring Boot
Three days to get a 'simple' OAuth integration working with Zapier. Here's what I learned about filter chains, race conditions, and PKCE.
How We Solved the Producer-Consumer Problem (For Blog Posts)
Writing blog posts is easy. Publishing them consistently is hard. Here's how we built a homebrewed CMS that handles the classic producer-consumer problem.
Caching API Responses at the Edge with Cloudflare Cache Rules
Your API is getting hammered. Same endpoints, same responses, thousands of requests. Here's how I used Cloudflare Cache Rules to serve API responses from the edge.
Why Your @Async Method Ignores @Transactional (And Leaks Internal Errors)
Production bug report: 'Why does the webhook error say Executing an update/delete query?' Here's how an innocent-looking @Async method broke everything.
Implementing Per-Seat Team Billing with Stripe
Adding team plans to a SaaS is tricky. You need per-seat pricing, plan upgrades/downgrades, webhook handling, and graceful degradation when payments fail.
Why Auth0 email_verified Was Missing from My Access Token
Spent an hour debugging why verified users were getting blocked. The culprit? Auth0 doesn't include email_verified in access tokens by default.
Cloudflare Bot Fight Mode Breaks Zapier OAuth (And How to Fix It)
After solving all the code issues with Zapier OAuth, I hit one more wall: Cloudflare's Bot Fight Mode. Here's the fix.
I Built a URL Shortener Because Bitly Made Me Angry
A senior dev once told me: 'Every side project is born from spite.' He was right. Here's the story of building jo4.io.
Async vs Sync Audit Logging: When to Use Which
When to use synchronous vs asynchronous audit logging in your application. A practical guide with real examples from production.
AWS ElastiCache vs MemoryDB: Which One Do You Actually Need?
A practical decision guide for choosing between ElastiCache and MemoryDB. TL;DR: If your data is ephemeral, use ElastiCache.
How I Tamed Claude Code with Pre-Tool Hooks (And You Should Too)
Using PreToolUse hooks to block dangerous git commands and cd in Claude Code. Keep your AI assistant productive without losing control.
I Built an API-First URL Shortener You Can White-Label
How I built jo4.io - a developer-friendly URL shortener with full API access and white-label support. Why Bit.ly pricing made me do it.
Jo4 Is Now on Zapier: From Design Doc to Live in 5 Weeks
OAuth2 with PKCE, REST hooks, a spam filter disaster, and a near-closed ticket. The full story of building and shipping our Zapier integration.
Getting Started with Jo4: Your Modern URL Shortener
Learn how to use Jo4 for URL shortening, QR codes, and link analytics. A complete guide to managing your links effectively.