Some projects have a longer arc than they look like on the surface. The ASN lookup tool at asn.ipinfo.app is one of them — what you see today is the latest iteration of something that predates even the first public version. Over a decade of running this service in different forms is a milestone worth writing down.

Here's the full arc.

Before the Beginning — Manually Curated Lists

Before any of this was public, it existed as a manually curated list with some automation to help build the block lists. The goal was the same as it's always been: make it easier to identify and block nefarious ASNs. But the operational cost was significant — maintaining accurate data by hand, with only partial automation, wasn't sustainable at any meaningful scale. Something had to change.

Where It Went Public — enjen.net/asn-blocklist/ (2015)

The first public version launched in 2015 at enjen.net/asn-blocklist/. Moving to a PHP-backed web tool was the answer to the sustainability problem — automate the list generation, make it accessible, stop doing everything by hand. The goal was practical: give people easy access to pre-baked block lists for different applications and services, built from ASN data. Rather than having to manually research which IP ranges belonged to a nefarious network and figure out how to express that in your firewall or application config, the tool did the legwork and handed you something ready to drop in.

It was basic, and it was clearly a utility that had grown out of a real operational need. The design wasn't winning any awards but that wasn't the point. It served a specific audience — network operators and administrators who needed to block by autonomous system — and it did that job.

The 2019 Rebuild — asn.ipinfo.app

In 2019, the tool moved to asn.ipinfo.app as part of the broader ipinfo.app suite. This was a meaningful step forward in scope. The blocklist-first framing gave way to a general-purpose ASN lookup tool — usable by anyone who needed to understand an IP prefix, trace an autonomous system, or look at what networks an ASN was announcing.

The underlying data was gathered through scraping. It worked, but it carried real maintenance weight — brittle to upstream changes, slow to keep current, and requiring active attention to catch silent failures. This version ran for seven years, which is a reasonable lifespan for a side project. Long enough to prove it was actually useful.

The backend ran against CockroachDB. At the time it was a good fit. Over time, CockroachDB moved to a licensing model that made it impractical to keep running for a free service — not something we were going to work around or pay for at this scale. The database was eventually going to need to go regardless of everything else.

The 2026 Rewrite — Node.js, New Data, New Look

Eleven years in, it was time for a proper overhaul. A few things needed to change at once: the technical stack, the data pipeline, and the database situation.

On the technical side, the app was rebuilt from scratch in Node.js and Express — dropping PHP entirely. The API surface stayed compatible by design; all the existing endpoints are drop-in replacements so anything calling the old API still works. A few endpoints tied to the old data model (archive, snapshots, peers) were retired and now return 410s with a pointer to asn-legacy.ipinfo.app for anyone who still needs them. The visual design got a full rework to match the cleaner aesthetic of the rest of the ipinfo.app suite.

The bigger change is the data source. The old scraping pipeline is gone, replaced by Atlas — a purpose-built data service we built specifically for this. Atlas gives us faster lookups, more accurate data, and quicker updates than the scraping approach ever could. The scraper was always chasing the state of the world; Atlas is designed to stay current. It also removes CockroachDB from the picture entirely — no more license concerns, no more cert management, no more a dependency that had been quietly getting harder to justify.

People Using It in the Wild

One of the more rewarding parts of running a niche utility for this long is seeing where it turns up. Over the years the service has been referenced by people solving real problems — DDoS response, bot blocking, firewall rule generation, router firmware scripts.

A few examples that have crossed our radar:

  • TCRF getting DDoSed — The Cutting Room Floor used ASN data to trace and respond to a DDoS campaign targeting their site.
  • Fortinet ASN blocklist thread — A community-sourced list of datacenter and hosting ASNs for Fortinet firewall rules, with our service cited as a reference.
  • Cheapskate's Guide — blocking bots — A practical guide to blocking scrapers and crawlers using ASN-level filtering.
  • AlliedModders forum thread — Game server administrators using ASN data for player filtering and ban management.
  • IPSet_ASUS — A router firmware script for ASUS routers that uses ASN data to build IP sets for network-level blocking.

This is the kind of usage that makes the service worth running. Real people, real problems, real infrastructure — not just a demo.

What Happened to enjen.net and the Old Site

enjen.net now redirects all traffic to asn.ipinfo.app and is on a path to full decommission. The domain has served its purpose; consolidating under ipinfo.app is the right long-term move.

For anyone who had a workflow built around the old interface, asn-legacy.ipinfo.app preserves a snapshot of the previous version. It's not actively maintained and search engines are pointed away from it, but it's there if you need it.

What's Next

The service will stay free. That's not a temporary decision — it's the baseline. If you find it useful and want to support it, there's a donate page, but there's no paywall coming and no plans for one.

On the roadmap: we want to bring in richer per-IP data alongside the existing ASN information. Prefix-level detail, reputation signals, more context for the kinds of investigations people actually do when they reach for a tool like this. Network operators, security researchers, abuse desk teams — there's real room to serve that audience better.

If you have ideas about what would be useful, we'd genuinely like to hear them. Reach out through the contact page.

Eleven years in, the foundation is in better shape than it's ever been. A clean codebase, a reliable data source, a design worth pointing people at, and no licensing baggage. That's a good platform to build on.