Spy on Competitors' Website: 9 Legal Ways to Do It

You can spy on a competitor's website legally by studying only what is public: its homepage, pricing and offer pages, how those pages changed over time in the Wayback Machine, its sitemap.xml and robots.txt, the tracking tags in its page source, its tech stack, its checkout flow up to payment, and the emails it sends after you sign up. Then you connect the site to its ads by searching its domain in the Meta Ad Library and the Google Ads Transparency Center.

I run this checklist whenever I pick up a new client, before I look at a single competitor ad. A website tells you what a business sells, how it prices, which offers it pushes and which ad platforms it is set up for. Here are the nine checks, in the order I do them.

Is it legal to spy on a competitor's website?

Looking at a public website is what websites are for. Reading pages, viewing the page source your browser already downloaded, checking archived copies and signing up for a newsletter are all things any visitor can do.

Where it stops being research is when you go past the public side: guessing passwords, poking at admin URLs, scraping in ways the site's terms forbid, pretending to be someone else to get private information, or placing fake orders to trigger refunds. None of that is needed, and none of it is in this guide. This is general guidance, not legal advice.

1. What do their homepage, pricing and offer pages tell you?

Start with the obvious pages and read them like a customer, then like a marketer.

• Homepage. What is the headline promise? Who is the hero image speaking to? What is the first call to action?
• Pricing page. How many tiers, which one is highlighted, is there a free trial, is annual billing pushed?
• Offer and collection pages. Bundles, "starter kits", guarantees, free shipping thresholds, current sale banners.
• About and FAQ pages. The objections they answer in their FAQ are the objections their customers raise.

Take full-page screenshots and date them. The value comes later, when you compare.

If you want to see the specific pages their ads send traffic to, that is a separate job with its own tricks. Our guide to finding competitor landing pages covers it, so I won't repeat it here.

2. How have their pages changed over time?

This is the check most people skip, and it is one of the most useful. The Wayback Machine at web.archive.org stores snapshots of many public pages going back years. Paste the competitor's homepage or pricing URL and you get a calendar of saved versions.

What I look for:

• Headline changes. If the homepage promise changed three times and then stopped changing, the last version is probably the one that worked.
• Price and tier changes. Price rises, new tiers, removed free plans.
• Recurring sales. The same sale banner showing up at the same time every year tells you their promo calendar.

Coverage varies. Big sites are snapshotted often, small sites less so, and some pages are never archived. Treat it as a strong hint, not a complete record.

3. What can sitemap.xml and robots.txt reveal?

Most sites publish a sitemap so search engines can find their pages. Try yourcompetitor.com/sitemap.xml, and if that doesn't load, check yourcompetitor.com/robots.txt, which often lists the sitemap location.

A sitemap is a public list of pages. It can show you product and collection pages you would never find through the menu, landing pages built for specific campaigns, location pages, and how many blog posts they have. Some sitemaps include last-modified dates, which tell you what they updated recently.

The robots.txt file shows which areas they ask search engines not to crawl. Read it for context, but respect it: a line that disallows a path is not an invitation to go digging there.

4. What does their blog or news section say about strategy?

A competitor's blog shows the keywords they are trying to rank for and the questions they think customers ask. Their news or press page shows launches, partnerships and funding. Their changelog, if they have one, shows what they are building.

I skim the last few months of posts and note the topics. Repeated topics usually mean a deliberate content push.

5. Which tracking tags are in their page source?

Right-click any page and choose "View Page Source", or open your browser's developer tools. You are looking at code your browser has already downloaded to show you the page.

Search the source for these markers:

Two caveats. A pixel only tells you the tracking is set up, not that money is being spent right now. And tags loaded through Tag Manager may not appear in the source, so I also check the Network tab in developer tools and filter for "fbevents" or "facebook.com/tr" while the page loads. Meta's own Pixel Helper extension and Google's Tag Assistant will show the same thing with less digging.

6. What does a tech lookup add?

Tools like BuiltWith and Wappalyzer read the public signals a site gives off and list the technology behind it: the ecommerce platform, email tool, reviews app, analytics, chat widget, payment providers and more. Wappalyzer also has a browser extension that shows this as you browse.

This matters because the stack reveals strategy. A reviews app means reviews are part of their selling. A subscription app means recurring revenue. A quiz app means they qualify visitors before recommending a product. Results can be incomplete or out of date, so confirm anything important by looking at the site yourself.

7. What can you learn from their checkout and email flows?

Checkout. Add a product to the cart and walk through checkout up to the payment step. Note upsells, order bumps, free shipping thresholds, payment options like buy-now-pay-later, and trust badges. Then stop. Don't complete fake orders, and never buy something just to cancel or refund it to see the flow.

Email. Sign up for their newsletter or discount popup with a real address you control. Over the next couple of weeks you'll see their welcome sequence, discount strategy and how often they email. If you add something to the cart, you may also see their abandoned cart emails. I use a dedicated research inbox so it doesn't clutter my main one.

If you genuinely want the product, buying it is fine and shows you the post-purchase emails and packaging too. Just treat it as a real purchase.

8. How do I see what ads a website is running?

Now connect the site to its ads.

Meta. Go to the Meta Ad Library at facebook.com/ads/library and search the domain as a keyword, then find the brand's Facebook Page and search that too. Domain searches catch ads linking to the site, including some run through creators or partner Pages. Our guide to searching the Meta Ad Library by website explains when each method works better.

Google. The Google Ads Transparency Center lets you look up an advertiser and see its search, display and YouTube ads. The walkthrough in how to check competitors' Google Ads covers it step by step.

While you're in the Meta Ad Library, check the "Started running on" date on each ad. Ads that have run for months are usually the ones that are working, which tells you which of the website's offers are actually getting traffic.

Here is how I keep what I find. Ads disappear from the Library when the advertiser stops them, so I save them the day I see them with our free extension, the Meta Ad Library Downloader. Its "Find all ads" mode collects every running ad for the search into one ZIP with a searchable swipe board and a CSV, so I can line the ads up against the website screenshots I took in step 1. The full guide to downloading Ad Library videos covers other ways to save them.

9. How do I keep watching the site without starting over?

One snapshot tells you where a competitor is. Repeated snapshots tell you where they're going.

I keep a simple log per competitor: date, homepage headline, main offer, price points, active sale, number of active Meta ads. Once a month I refresh it. Changes on the site usually line up with changes in the ads, and our guide to tracking competitor promotions on Facebook shows how to catch sales as they launch.

If you're not sure who to put on the list in the first place, start with identifying your real competitors.

Which check answers which question?

FAQ

Is it legal to spy on a competitor's website?

Viewing public pages, page source, archived copies and newsletters is normal competitive research that any visitor can do. Going past the public side, such as logging into accounts you don't own or abusing refunds, is not. This is general guidance, not legal advice.

How can I see what ads a website is running?

Search the website's domain and the brand's Page name in the Meta Ad Library, and look the advertiser up in the Google Ads Transparency Center. Together they show active Facebook, Instagram, Google Search, display and YouTube ads.

Does a Meta pixel on a site prove they run Facebook ads?

No, it only shows the tracking is installed. Most brands with a pixel do advertise on Meta at some point, but the Meta Ad Library is the place to confirm whether ads are running right now.

How do I see old versions of a competitor's website?

Paste the page URL into the Wayback Machine at web.archive.org and pick a date from the calendar. Coverage is better for larger sites, and some pages are never archived.

What should I never do when researching a competitor's site?

Never try to access login-protected areas, guess passwords, impersonate someone to get private information, or place fake orders to trigger refunds. Also respect the site's terms and robots.txt, and never copy their content into your own pages or ads.