9 Free Developer Tools Every Developer Should Bookmark in 2026
Stop googling the same things every day. These 9 tools replace 20 bookmarks and save you hours per week. All free, no ads, no signup.
Every developer has the same routine: open terminal, type dig MX example.com, realize you forgot the flags, google "DNS lookup tool", close 3 ad-infested sites, finally find one that works. Bookmark it. Repeat tomorrow with a different tool.
I built Korpo.Pro to solve this. 51 free developer tools in one place — but you don't need all 51. Here are the 9 you'll actually use every week.
1. 🌐 DNS Lookup — The One You'll Use Most
Check A, AAAA, MX, NS, TXT, CNAME, and SOA records for any domain. No dig memorization needed. Just type the domain and get everything.
2. 📧 Email Checker — Stop Emails Going to Spam
Full deliverability audit in 5 seconds. Checks MX records, SPF, DKIM, DMARC, and 5 blacklists. Scores your domain /100 and tells you exactly what to fix.
3. 🔍 SEO Analyzer — Fix Your Meta Tags
Enter any URL and get its title, description, OG tags, Twitter cards, robots, and canonical. Know exactly what Google and social media see.
4. { } JSON Formatter — Because Minified JSON Is Unreadable
Paste ugly JSON, get pretty JSON. Validate, format, or minify in one click. Works with massive payloads.
5. 🔒 SSL Checker — Never Miss a Certificate Expiry
Check any domain's SSL certificate — expiry date, issuer, SAN domains, chain validation. Know when your cert expires before your users do.
6. 🔣 Base64 Codec — Encode/Decode Instantly
Decode that Base64 blob someone sent you. Or encode something quickly. No terminal, no decoding websites with trackers.
7. 🔎 WHOIS Lookup — Who Owns That Domain?
Registrar, creation date, expiry date, nameservers. Everything you'd normally pay for or dig through ICANN for.
8. 📍 IP Lookup — Geolocate Any IP
Get country, city, ISP, hostname, and abuse contact for any IP address. Useful for debugging, security, or just curiosity.
9. 💀 Dead Man's Switch — Because Cron Jobs Fail Silently
Create monitors that expect a ping every X minutes. If the ping doesn't arrive — you get an email alert. Free tier: 5 monitors with 5-minute check intervals.
There Are 42 More Where These Came From
These 9 are the greatest hits. But the full toolkit has 51 tools — CSS/JS minifier, QR code generator, password generator, redirect chain checker, DMARC parser, color picker, contrast checker, URL encoder, Markdown-to-HTML converter, image-to-Base64, UTM builder, bulk WHOIS, hash generator, subnet calculator, and more.
📋 Want the full list?
Browse all 51 tools → — categorized, with descriptions.