The Hidden $500/mo Cost of Rolling Your Own Bulk URL Checker

The cheap version of “just write a script” usually ends up costing $500 to $1,500 per month, not counting the engineer who maintains it.

That estimate is going to look high if you only consider the proxy bill. It is going to look low if you have ever owned a URL checker through an incident at 3am. Either way, the numbers are worth doing honestly before you commit to building. This post lays them out: residential proxies, engineering hours, monitoring, on-call, and the long tail of edge cases.

The line-by-line monthly cost

Here is a realistic monthly bill for a self-hosted bulk URL checker that runs about 100,000 URL checks per month, the rough scale of a single-agency or small-SaaS workload.

Residential proxies (Webshare Pro tier)            $90/mo
Server (1 x DigitalOcean droplet, 4GB)             $24/mo
Postgres or Redis for job state (managed)          $15/mo
Object storage for result files (S3, ~5GB)         $1/mo
Error monitoring (Sentry hobby)                    $26/mo
Uptime monitoring (Better Stack)                   $0  (free tier)
Engineer time (avg 4h/mo maintenance @ $100/h)     $400/mo
                                                  ----------
                                                   $556/mo

That is the steady-state bill, after the initial build is done. The initial build itself is a separate line: roughly two to four engineer-weeks of focused work to get to “mostly works for typical inputs”.

The headline cost is the proxies. The hidden cost is the engineer hours after launch.

What “four hours of maintenance” actually looks like

Four hours per month sounds light until you list out what fills them:

• A new CDN provider starts blocking your proxy IPs. You rotate to a different proxy tier, update your DNS-fronting config, and re-run a stuck job.
• Cloudflare changes a fingerprinting signal. Your HEAD requests start returning 403s where GET would still work. You add a fallback path.
• A customer reports a job that “hung at 78%” for two hours. You SSH in, find a zombie worker, kill it, and write a watchdog cron so it does not happen again.
• Webshare changes their billing model and your usage spikes. You add a per-job credit cap and a daily spend alert.
• Someone reports broken-link false positives on a site that uses JavaScript redirects. You add a Playwright fallback for the URLs that returned 200 with a suspicious body.

None of these is a crisis. All of them combined is a job that you do not get to ignore. Four hours per month is generous; the real number for most teams is closer to one full day per month, plus the occasional fire drill.

The case where build wins

The math flips when at least one of the following is true:

• You have very specific compliance requirements. If the URLs you are checking are inside a healthcare or financial product, sending them through a third-party service may not be acceptable. Self-hosting is the answer.
• You already have the infrastructure. If your team already runs residential proxies, a job queue, and a Postgres cluster for adjacent reasons, the marginal cost of adding a URL checker is genuinely small.
• You will hit absurd scale. Above roughly 5 million URLs per month, dedicated infrastructure starts to outprice managed services. We are happy to admit it.
• You enjoy this work. Some engineers genuinely like the problem and want to own it. That is a valid reason as long as your manager agrees the time spent is worth it.

The case where buy wins

Buy is the obvious choice when:

• URL checking is not your core product. If you are an SEO agency, a docs platform, or a marketplace, the URL checker is a means to an end. Time spent maintaining it is time not spent on the product your customers actually pay for.
• You want to ship faster than four weeks. A managed service is a one-day integration. A homegrown system is a four-week build before it works for one customer.
• Your team is small. A two-person team should not own infrastructure that breaks at 3am. The engineer who fixes it is the engineer who is not shipping the next feature.
• You want predictable cost. A managed service charges per URL. Your cost scales with usage instead of with engineer-time, which is a less surprising line item to defend at budget review.

What Bulk URL Checker costs at the same workload

For the 100,000 URLs/month example above, our pricing comes out to:

Bulk URL Checker Pro plan                          $29/mo
  Includes 50,000 URLs/month
Top-up credit packs to cover the next 50K URLs     ~ tens of $/mo
                                                   (rates on the pricing page)
                                                  ----------
                                                   well under $100/mo total

Engineer-time line: 0. We handle proxy rotation, retry classification, soft-404 detection, the queue, the dashboard, the alerts. Your engineer fixes nothing.

That is not always the right comparison. If you are checking 5,000 URLs per month, our Starter plan at $9/month covers it and the “build” column does not get cheaper than the proxy bill alone. If you are checking 5 million URLs per month, we are happy to quote you, but at that scale your own infrastructure is probably defensible.

The interesting case is the 50K to 500K range. That is where most agencies, SaaS, and docs teams live, and that is where the math most decisively says “buy.” See the full pricing for the exact tiers and credit-pack rates.

The hidden cost we don't talk about

The cost that does not show up on the spreadsheet is the cost of being wrong at the wrong moment. A homegrown checker that quietly misses 200 broken backlinks during a client audit is one thing. A homegrown checker that miscounts redirects right before a major migration is something else entirely. The dollar amount of being wrong is often larger than a year of subscription fees.

Buying does not eliminate this risk, but it does shift it. When a managed service has a bad day, your customer sees a degraded experience, you file a ticket, and you go back to your real work. When your own infrastructure has a bad day, your customer sees the same degraded experience and you are also the one staying up to fix it.

How to decide

Three questions, in this order:

1. What scale do we actually need? Be honest. Include peak weeks, not average. If under 500K URLs/month, buy is almost certainly cheaper.
2. What is our engineer-hour rate? Apply the rate to the realistic maintenance time, not the optimistic version.
3. What happens when this breaks at 3am? If the answer involves you personally, factor that into the build cost. If the answer is “the vendor handles it,” the buy column gets a credit you do not usually account for.

If buy looks right, our REST API and the Python SDK are a one-day integration. The first 300 URLs are free, no credit card. If build looks right, the next post in this series (Soft 404 detection: when HTTP 200 actually means broken) covers one of the trickiest pieces you will need to get right.