You already know the standard playbook: email follow-ups, SMS drip campaigns, in-store tablet prompts.These channels are saturated, flagged by spam filters, and increasingly ignored.
Broken Link Building with Free Tools
The Wayback Machine’s CDX API: A Free, Scalable Broken Link Building Ladder
Broken link building remains one of the few white-hat link acquisition tactics that still offers asymmetric returns for startups with zero budget. The math is simple: find a dead resource page, identify the website that linked to it, and convince that webmaster to swap the stale URL for your living, breathing equivalent. But the conventional workflow — manually checking every resource page, scraping with browser extensions, and praying for a 404 — scales about as well as a single-threaded crawler on a 10GB sitemap. That is where the Internet Archive’s CDX API comes in, turning a tedious archaeology project into a programmatic mining operation that you can run on a laptop with nothing more than curl and a spreadsheet.
Most marketers know the Wayback Machine as a “view old pages” tool. Fewer realize its CDX server exposes a queryable index of every captured URL, timestamp, and HTTP status code across hundreds of billions of archived snapshots. For the broken link builder, this means you can pull a complete historical inventory of any website’s outbound links, filter for URLs that returned 200 at the time of capture, and then re-check those same URLs today. The delta is your defunct link goldmine. And the API is completely free, with generous rate limits for responsible requests.
To start, you need a seed set of what I like to call “link graveyards” — pages that naturally collect external references to resources. Think university reading lists, curated industry directories, “useful tools” roundups from 2016, and open-source project documentation. Using CDX, you query for all snapshots of that seed page, then parse the archived HTML from the most recent snapshot before the page’s death, extracting every outbound href. Python’s requests and BeautifulSoup handle this in twenty lines, but if you want to avoid touching code, Google Sheets’ IMPORTXML can pull href attributes directly from an archived URL. That gives you a static list of historical link targets.
Next comes the verification phase. You need to know which of those targets are currently returning 404 or 410. Free tools like HTTPStatus.io accept batches up to 100 URLs, and you can write a simple shell loop with curl --write-out ’%
