Similarweb vs SpyFu

What Similarweb is

Similarweb estimates website traffic, referral sources and audience overlap for any domain. It is one of the few ways to size a competitor you have no access to, which is why it is used in market research and pitch work. Everything it reports is an estimate from panel and clickstream modelling, so treat the direction and the ratios as the signal, not the absolute numbers.

What SpyFu is

SpyFu shows which keywords competitors bid on and rank for, with historical data going back years. That archive is the reason to use it: rather than a snapshot of today's rankings, you can see how long a competitor has defended a term, which ad copy they kept running, and which campaigns they abandoned. Coverage is strongest for the US market and thinner elsewhere, and the data is modelled rather than taken from ad accounts, so treat the figures as direction rather than measurement.

What Similarweb is built to do

Traffic estimates

Models visits, engagement and growth for domains you do not own.

Traffic sources

Splits estimated traffic across search, referral, social and direct.

Audience overlap

Shows which other sites a domain's visitors also use.

What SpyFu is built to do

Competitor keyword history

Years of ranking and bidding history for a domain, not just the current position.

Ad copy archive

Every paid advert a competitor has run, which shows the messages they kept and dropped.

Keyword gap analysis

Terms competitors rank for and you do not, ranked by opportunity.

Unlimited searches

Plans are not metered per lookup, which suits exploratory research.

Choose Similarweb if

• Marketing and strategy teams sizing competitors and markets.

Choose SpyFu if

• Competitor keyword and ad research where the Pro tier's uncapped search results and exports matter
• Trying a paid SEO tool with a 30-day money-back guarantee instead of a free trial
• Agencies tracking many domains — the top tier allows unlimited projects and 50k tracked keywords

Skip SpyFu if

• You want a free tier — SpyFu has none; the entry plan is $39/month, or $29/month billed annually
• The Basic caps are too tight for you: 10k search results, 10k export rows, 1 tracking project and 5k tracked keywords
• Your market is outside the US, where data accuracy varies and coverage is weaker

Similarweb: pros & cons

• Competitive traffic estimates in one place
• Channel breakdown and referrers
• Useful for market sizing
• Estimates, not measurements — accuracy varies
• Expensive for full access
• Small sites have unreliable data

SpyFu: pros & cons

• Deep historical ad and keyword data
• Inexpensive relative to rivals
• Useful competitor ad history
• Data accuracy varies by market
• Interface feels dated
• Weaker outside the US