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Part 6 of 7 · Broken link reporter series ~5 min read

What the broken link reporter costs

A crawl is bandwidth and compute, both of which are cheap, and there is no model in this system at all. Two thousand pages weekly is a mature small-business site; forty thousand is four weekly crawls of a large one. Here is where each cent goes.

Key takeaways

  • About $13 a month at 8,000 pages. Roughly $62 at 40,000 pages.
  • One Bedrock read per page crawled is the only line that scales. Everything else is rounding.
  • Nothing is always-on, so a quiet month genuinely costs almost nothing.
  • No model, and outbound bandwidth is the only line that scales with site size.
  • The duplicate test runs before the read, so resends are free.
  • The three real risks: a retry loop, storage nobody expires, and a bigger model than the job needs.

The bill at three volumes

These are US East prices at the time of writing, at three volumes that bracket most small businesses. Find the bar closest to your own and read across.

Monthly cost of the broken link reporter at three volumesA stacked bar chart with three bars, one per volume tier: 2,000 pages totalling about $4, 8,000 pages totalling about $13, and 40,000 pages totalling about $62. Each bar is stacked from bands. The largest and fastest-growing is Bedrock, one read per page crawled, in teal. Then SES for the messages, in pink. Then S3 and DynamoDB storage in green. Then a fixed orange band for Secrets Manager and AWS Budgets, which is eighty-six cents at every volume. Then a grey band for Lambda, SQS and CloudWatch. A note says the read is the only bar that grows with the business and the orange band never moves.$0$20$40$60$80~$4.262,000 pages~$13.328,000 pages~$61.6540,000 pagesBedrock — one read per page crawledSES — asks, results, receiptsS3 + DynamoDBFixed — Secrets Manager, BudgetsLambda, SQS, CloudWatchThe read is the only bar that grows with the business. The orange fixed band never moves.
Fig 1. The monthly bill at three volumes. The teal band — one model read per page crawled — is the only part that grows; the orange fixed band is the same 86 cents at every volume.

Line by line

LineAt 8,000 pagesHow it scales
Bedrock read$0.00Linear. One call per page crawled, roughly 1,800 in and 200 out tokens.
SES$4.00Linear. About 0.002 messages per page crawled.
DynamoDB + S3$1.56Storage grows with what you retain, not with throughput.
Lambda + SQS$0.12Linear, and effectively free at this scale.
CloudWatch$0.16Flat, if you set retention. Unbounded if you do not.
Secrets Manager$0.40Flat. One secret, $0.40 a month.
AWS Budgets$0.46Flat. Two actions, so you find out before the bill does.

There is no read line: nothing here calls a model. The cost is Lambda duration and outbound requests, and both are small enough that the fixed band dominates until the site is very large.

The three ways this bill surprises you

Every one of these has happened to somebody, and all three are cheap to prevent.

  • An unbounded crawl. A calendar widget or a faceted filter turns two thousand pages into two hundred thousand, and the Lambda time is the smallest part of that problem. The page cap is the control.
  • Checking every link on every page. Without the per-run URL cache, a site-wide footer with twelve external links costs twenty-four thousand requests instead of twelve, and will get you blocked.
  • Log retention left at never. A crawl produces a log line per page by default, which at eight thousand pages a week is the entire bill within a year.

What it costs when nothing happens

This matters more than the headline number for a seasonal business. In a month with nothing to process the bill is the fixed band: Secrets Manager at forty cents, AWS Budgets at forty-six, and a few cents of storage. Call it a dollar. There is no instance to stop and nothing to remember to turn off.

The monthly bill at four volumes plus one failure modeA horizontal row of five boxes. Quiet month, about one dollar. 2,000 pages, about $4. 8,000 pages, about $13. 40,000 pages, about $62. And one bad retry loop, about two hundred dollars. A note says four of these are the design working and the fifth is a missing dead-letter queue.THE BILL, AT A GLANCEQuiet month~$12,000 pages~$48,000 pages~$1340,000 pages~$62One bad loop~$200Four of these are the design working. The fifth is a missing dead-letter queue.
Fig 2. The bill at a glance, including the one that is not a volume at all. A retry loop with no dead-letter queue costs more than every legitimate use of the system put together.
  • Management
  • Analytics
  • Front-end & mobile

Set these on day one

  • A dead-letter queue on every SQS queue, with a maximum receive count of three.
  • Thirty-day retention on every CloudWatch log group. There is no default that is safe.
  • An S3 lifecycle rule on the object prefix, tiering at 90 days and expiring at your actual record-keeping horizon.
  • Two AWS Budgets actions — one that emails at half your expected spend, one at double it. The second is how you find out about a loop in an hour instead of a month.
  • Provisioned concurrency: none. Nothing here is latency-sensitive enough to justify paying for a warm function.

Next: the same system drawn for engineers — service names, resource identifiers, IAM scopes, table schemas and the model id.

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