Similarweb

What it is

Similarweb estimates digital traffic and engagement for any website and app — visits, sources, top pages, audience overlap, and how share is shifting between players in a category. For a PM this is the closest thing to seeing a competitor’s dashboard from the outside: you can sanity-check “are they actually growing,” find which channels drive their acquisition, and get a defensible top-down input for market sizing.

Our verdict

The go-to when your competitive question is quantitative rather than qualitative. It’s genuinely useful for market-share framing and for catching a competitor’s growth (or decline) before it shows up in the press. The traffic-source breakdown is the standout — it tells you whether a rival lives on SEO, paid, or direct, which shapes how you’d compete. The free browser extension gives you a taste, but real work needs a paid seat.

Where it falls short: the numbers are modeled estimates, not truth — directionally reliable for large sites, shaky for small ones, and you should never quote a single figure as fact without a hedge. The free tier is deliberately shallow (headline numbers, no drill-downs), and anything team-sized is quote-led “talk to sales,” so budget on real work is opaque until you’re in a call.

Get value in 10 minutes

1. Look up a domain on the free tier first (or install the free Chrome extension) — for a quick “are they growing?” sanity check you often never need to pay.
2. Enter a competitor’s domain and open Traffic & Engagement → note total visits, trend, and average visit duration.
3. Open Marketing Channels to see their SEO/paid/direct/referral split — this tells you where they’re vulnerable.
4. Use Compare to line up 3–5 rivals on visits and share, and screenshot the trend chart straight into your market-sizing or QBR deck (with a “modeled estimate” caveat).