404 Link Finder

About

# 404 Link Finder — Find & Visually Locate Broken Links, Plus Bulk URL Scanning

## Find every broken link on a page — and actually see where it is

404 Link Finder is a fast, focused Chrome extension that does one job exceptionally well: it finds broken links and shows you exactly where they are. Whether you are auditing a single article before you publish it, cleaning up an old site full of dead outbound links, or checking dozens of URLs at once, 404 Link Finder turns a tedious manual chore into a few clicks. It checks the real HTTP status of every link, flags anything broken, and either paints the result directly onto the page in front of you or compiles a clean, exportable report you can hand to a colleague.

Broken links are everywhere, and they quietly hurt. They frustrate readers, leak away SEO value, make a site look neglected, and break the user journeys you worked hard to build. The problem is that finding them by hand is miserable — you would have to click every link, wait, hit back, and remember which ones failed. 404 Link Finder removes all of that friction. It does the clicking for you, in parallel, and reports back in seconds.

## Two modes, one simple popup

The extension has a small, clean popup with two complementary modes. Pick the one that fits the task.

### Mode 1 — This Page (Visual Locator)

This is the mode you reach for when you are looking at a specific page and want to know, right now, which of its links are dead. Click **Scan This Page** and the extension reads every `<a href>` link in the live page — including links added dynamically by JavaScript, because it works against the real, rendered DOM rather than raw source. Each link's true HTTP status is checked, and then the magic happens on the page itself.

Every broken link gets a bright **red outline and a "404" badge** drawn directly over it, so you can see at a glance where the problems are without leaving the page or cross-referencing a list. Found a long article with one dead link buried in the middle? You do not have to hunt for it. Use the **Prev / Next** buttons in the popup to smoothly scroll from one broken link to the next, and each jump fires a brief pulse animation so your eye lands on the exact spot instantly. You can also click any entry in the results list to jump straight to that link on the page. When you are done, download a CSV report of everything that was found.

This visual approach is what sets 404 Link Finder apart from typical link checkers that only hand you a flat list of URLs with no sense of where they live on the page. Here, the page is the report.

### Mode 2 — Bulk Check (Many URLs at Once)

When you need to audit more than one page, switch to Bulk Check. Paste a list of URLs, one per line, and the extension goes to work: for each URL it fetches the page, extracts every link it contains, checks the status of every one of those links, and reports back all the broken ones it found. This lets you sweep an entire set of pages — a sitemap, a list of blog posts, a batch of landing pages — in a single run, without opening any of them yourself.

A live progress bar shows you how far along the scan is, and a cancel button lets you stop at any time if you started something larger than you meant to. When the run finishes, export the results as either a **CSV** (perfect for spreadsheets) or **JSON** (perfect for feeding into other tools or scripts). The report includes the source page, the broken link, and the exact status code returned, so you know not just that something is wrong but precisely what.

## Built for speed and accuracy

404 Link Finder is engineered to be both quick and correct.

- **Real status codes, not guesses.** The extension actually requests each link and reads the HTTP response status. It first tries a lightweight `HEAD` request, which asks only for headers and avoids downloading the whole page. If a server does not support `HEAD` (some don't), it automatically falls back to a `GET` request so the check still succeeds. This gives you accurate results while keeping bandwidth low wherever possible.

- **Parallel checking.** Links are checked several at a time — up to eight concurrent requests — so a page or batch with many links resolves in a fraction of the time a one-at-a-time checker would take. You spend seconds waiting, not minutes.

- **Sensible timeouts.** Each request is capped at twelve seconds. A single slow or hanging server will not stall your entire scan; it is recorded and the run moves on.

- **Honest about more than just 404.** While "404" is the headline, the extension treats any 4xx or 5xx response as broken and shows you the exact code. That means you also catch 403 walls, 410 Gone, 500 server errors, and other failures — not only the literal 404s. The status next to each link tells you which is which.

- **Clear handling of blocked sites.** Some sites aggressively block automated requests with Cloudflare challenges or 403 responses. Rather than silently mislabeling these, the extension surfaces them as blocked or as their actual non-404 status, so you can tell a genuinely dead link apart from one that simply refused an automated check.

## Who it's for

- **Bloggers and content writers** doing a final link check before hitting publish.
- **SEO specialists** auditing internal and outbound links across many pages, where broken links waste crawl budget and link equity.
- **Web developers and QA engineers** verifying that a build, migration, or redesign did not leave dead links behind.
- **Site owners and editors** maintaining older sites where outbound links rot over time as other sites move or disappear.
- **Anyone** who has ever clicked a promising link only to hit a dead end, and wished they could catch those before their readers do.

## How it works under the hood

404 Link Finder is built on Manifest V3, the current Chrome extension platform, and is organized into a few small, transparent pieces.

The **popup** (its HTML, CSS, and JavaScript) is the interface you see when you click the toolbar icon — the two mode tabs, the scan buttons, the progress bar, the results list, and the export buttons.

The **content script** is injected into the active tab only when you ask it to scan that page. It collects the `<a>` tags from the live DOM, draws the red outlines and "404" badges on broken links, and handles the smooth scroll-to-link and pulse animation when you step through results.

The **background service worker** is where the network checking happens. It performs all the `fetch()` requests — `HEAD` first, falling back to `GET` — reads the returned status codes, and manages the concurrency that makes scans fast. Centralizing the fetches in the service worker is also what lets the extension check cross-origin links reliably.

In bulk mode, the worker fetches each page's HTML and extracts its links to check them. Note that bulk mode reads the raw HTML, so links injected later by JavaScript on those remote pages are not seen in bulk mode — for fully dynamic pages, the single-page visual mode, which runs against the live rendered DOM, is the right tool.

## Privacy: your data stays yours

404 Link Finder is built to respect your privacy completely.

- **No data collection.** The extension does not collect, transmit, sell, or share any information about you, the pages you scan, or the links it checks. There is no analytics and no telemetry.
- **No external servers.** There is no backend belonging to this extension. The only network requests it makes are the link checks themselves — sent directly to the sites whose links you are testing, exactly as your browser would if you clicked them — and nothing is routed through any third party.
- **Everything runs locally.** Scanning, status checking, highlighting, and report generation all happen on your own machine, in your own browser.
- **Reports are saved only when you ask.** CSV and JSON files are written to your computer's Downloads only when you click export. Nothing is uploaded anywhere.
- **Minimal stored data.** The only thing kept in local extension storage is lightweight state such as your last results or preferences, so the popup behaves sensibly between uses. No browsing history or personal data is stored.

## Honest limitations

In the spirit of transparency:

- Bulk mode extracts links from raw HTML and will not catch links that a remote page adds dynamically with JavaScript after load. Use single-page visual mode for those.
- Sites protected by Cloudflare or similar may block automated checks; those appear as blocked or as their actual status rather than as confirmed-good links.
- A small number of servers behave unusually with automated requests; the `HEAD`-then-`GET` fallback handles most, but the occasional edge case may report a status that differs from what a full browser visit would show.
- The extension reports 4xx and 5xx responses as broken so you see all errors, not only literal 404s. Read the status code shown beside each link for the specifics.

## Get started in seconds

Open any page, click the 404 Link Finder icon, and press **Scan This Page** to see broken links light up in front of you — or switch to **Bulk Check**, paste your list of URLs, and let it sweep them all. Export a clean report when you are done. No sign-up, no account, no configuration. Just fast, accurate, visual broken-link detection whenever you need it.

Stop letting dead links quietly undermine your pages. Find them, see them, fix them — with 404 Link Finder.