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📰 Dev.to · John Leslie

9 articles · Updated every 3 hours · View all reads

All Articles 128,009 Blog Posts 132,883 Tech Tutorials 33,049 Research Papers 24,713 News 18,159 ⚡ AI Lessons

26 of 39 AI Companies Use SPF Softfail — Their Email Can Be Spoofed

Dev.to · John Leslie 🔐 Cybersecurity ⚡ AI Lesson 2mo ago

26 of 39 AI Companies Use SPF Softfail — Their Email Can Be Spoofed

I queried the DNS records for 39 AI companies — labs, safety orgs, tooling companies — and checked...

I analyzed stripe.com and github.com — their DNS reveals their email provider, hiring tools, and security posture

Dev.to · John Leslie 🔐 Cybersecurity ⚡ AI Lesson 2mo ago

I analyzed stripe.com and github.com — their DNS reveals their email provider, hiring tools, and security posture

I can tell you Stripe uses Greenhouse for hiring before they have posted a job listing. I can tell...

I Tested 7 Free AI Startup Idea Validators — Most Are Useless, 3 Are Worth Your Time

Dev.to · John Leslie 🚀 Entrepreneurship & Startups ⚡ AI Lesson 2mo ago

I Tested 7 Free AI Startup Idea Validators — Most Are Useless, 3 Are Worth Your Time

Same startup idea, 7 different AI validators. Full disclosure: I built one of them. Here is what each actually outputs.

How to Validate Your Startup Idea for Free in 2026 — A Step-by-Step Framework

Dev.to · John Leslie 🚀 Entrepreneurship & Startups ⚡ AI Lesson 2mo ago

How to Validate Your Startup Idea for Free in 2026 — A Step-by-Step Framework

Most startup ideas fail not because they're bad, but because founders skip validation. Here's a free,...

I Built 5 Free AI Tools That Replace $500 in Startup Consulting

Dev.to · John Leslie 2mo ago

I Built 5 Free AI Tools That Replace $500 in Startup Consulting

I built a set of free AI tools that help startup founders think through the early-stage decisions...

Google Places API Now Costs $275/Month — Here's a Free Alternative

Dev.to · John Leslie 📣 Digital Marketing & Growth ⚡ AI Lesson 2mo ago

Google Places API Now Costs $275/Month — Here's a Free Alternative

Google Places API pricing hit a breaking point in 2026. The basic "Essentials" tier starts at...

Free Google Places API Alternative: 37 Business Categories, No API Key

Dev.to · John Leslie 📣 Digital Marketing & Growth ⚡ AI Lesson 2mo ago

Free Google Places API Alternative: 37 Business Categories, No API Key

Google Places API removed its free tier in February 2025. The new pricing starts at ~$275/month for...

I made a free REST API that turns 'find cafes in Paris' into structured JSON

Dev.to · John Leslie ⚡ AI Lesson 2mo ago

I made a free REST API that turns 'find cafes in Paris' into structured JSON

A free REST API for finding businesses by location. Try it curl...

Are Prediction Markets Well-Calibrated? I Analyzed 7,661 Resolved Polymarket Markets

Dev.to · John Leslie 📊 Data Analytics & Business Intelligence ⚡ AI Lesson 2mo ago

Are Prediction Markets Well-Calibrated? I Analyzed 7,661 Resolved Polymarket Markets

By John Leslie Prediction markets are booming. Polymarket alone processes billions in volume. But a...