Why Semrush and Similarweb Different: Not the Same Tool

They Were Built for Different Jobs

This is the part most comparison articles skip entirely — and it’s the most important thing to understand.

Semrush started as an SEO research tool. Its core DNA is search: keyword rankings, backlink profiles, on-page optimization, and content gaps. When Semrush estimates traffic for a domain, it’s doing so through a search-first lens — it looks at what keywords a site ranks for, multiplies by estimated click-through rates and search volumes, and produces a number that reflects organic search-driven traffic specifically.

Similarweb, on the other hand, was built as a market intelligence platform from the start. Its goal was never SEO. It was built to answer questions like: how much total traffic does a website get, from all channels combined? How does its audience behave? What’s the competitive landscape in a given industry?

Same surface question (“how much traffic does this site get?”), completely different methodology, completely different answer.

That’s not a malfunction. That’s by design.

Where the Data Actually Comes From

Understanding the discrepancy means understanding what each tool uses as its raw material.

How Semrush Builds Its Traffic Estimates

Semrush constructs traffic estimates from keyword data — specifically, it tracks keyword rankings across its own crawl database, applies click-through rate models based on ranking position, and multiplies by estimated monthly search volumes pulled from its keyword research infrastructure.

The result is a traffic estimate that’s reasonably accurate for organic search traffic — particularly for sites where Google search is a dominant acquisition channel. But it’s inherently incomplete for sites that rely heavily on direct traffic, social referrals, email newsletters, or paid channels.

In my five years of using Semrush across client projects, I’ve consistently found that its organic traffic estimates are solid for content-heavy sites where search is the primary driver. For e-commerce brands running aggressive paid campaigns or viral social content? The gap between Semrush’s number and reality grows considerably.

How Similarweb Builds Its Traffic Estimates

Similarweb takes a fundamentally different approach. It draws from a combination of sources: anonymized panel data (browser extensions, apps, opted-in user data), ISP-level data partnerships, and publicly available web crawl signals. The goal is to estimate total traffic across all channels — not just search.

That breadth is both Similarweb’s strength and its limitation. For large domains with millions of monthly visitors, its estimates tend to be remarkably close to reality. For smaller sites under ~50,000 monthly visitors, the panel size gets thin, and the estimates can swing significantly.

Similarweb is also more explicit about this limitation than most people realize. Their own documentation acknowledges that free-tier data is a high-level sample — the deeper you go in their paid tiers, the more granular and reliable the data becomes.

The Specific Features That Set Them Apart

Both tools have expanded significantly over the past few years. The gap between them isn’t just about traffic estimation methodology anymore — it’s about the entire product philosophy.

What Semrush Is Actually Good At

Semrush’s core strength remains keyword and search intelligence. Its keyword database covers billions of terms. Its backlink analytics, technical site audit, rank tracking, and content optimization tools are genuinely class-leading for SEO work.

The more recent Semrush One plans also fold in AI visibility tracking — monitoring how your brand appears in AI-generated responses from ChatGPT, Gemini, Perplexity, and others. That’s a meaningful evolution beyond pure SEO. But the foundation is still searching for data, and everything builds from there.

If your question is “why isn’t my page ranking” or “what keywords should I target next quarter,” Semrush gives you the most actionable answers.

What Similarweb Is Actually Good At

Similarweb’s strength is market-level intelligence. If you want to understand how an entire industry segment is moving — which players are gaining traffic share, where audiences are coming from, what the competitive landscape looks like from a 30,000-foot view — Similarweb has depth that Semrush simply doesn’t match.

Its Web Intelligence suite covers competitive intelligence, audience demographics, marketing channel breakdowns, and now AI brand visibility tracking through its AEO Intelligence features (available on the Competitive Intel & SEO & AEO tiers at $333/mo billed annually). The Retail Intelligence product goes even further for eCommerce, tracking Amazon seller data, category management, and shopper behavior signals that are irrelevant to an SEO tool but invaluable to a retail strategist.

This isn’t something Semrush is trying to compete with — and vice versa.

Why the Traffic Numbers Look So Different

Let’s get concrete about why the discrepancy exists when you look at the same domain in both tools.

Scenario: You pull a mid-size SaaS company (say, 200,000 monthly visitors according to their own GA4 data) in both tools.

• Semrush shows: 85,000 monthly visits
• Similarweb shows: 210,000 monthly visits

Neither number is wrong in isolation. Semrush is estimating organic search traffic, and organic accounts for about 40% of this company’s actual traffic mix. Similarweb is estimating total traffic across all channels and lands closer to the real number because it includes direct, social, referral, and paid.

Comparing those two numbers directly makes no sense. It’s like comparing miles driven to total distance traveled, including flights. Different measurement. Different scope.

This is the explanation most users never get — and it’s why “which tool shows accurate traffic data” is genuinely the wrong question to ask.

My Actual Workflow Using Both Tools

Here’s the thing — after five years of working with Semrush across dozens of projects, I don’t treat these two tools as competitors at all. They slot into completely different stages of my research process.

Whenever I start working on a new website — whether it’s a fresh build or an existing site I’m taking on — I open Semrush first. I use it to map the keyword landscape, understand what competitors are actually ranking for, identify content gaps, and build a research foundation that shapes the entire SEO strategy. The keyword data depth, the competitor analysis, and the site audit — all of it runs through Semrush from day one. After five years, it’s genuinely become the non-negotiable first step in how I approach any new project.

Similarweb serves a different purpose in my workflow. I use it at the research stage for getting a fast read on a domain’s overall traffic picture — total visits, channel breakdown, audience geography — before deciding how deep to go. The browser extension is useful for a quick on-the-fly ballpark, but where Similarweb actually earns its place is when I’m doing market-level competitor research: understanding which channels a competitor is leaning on, whether their traffic is search-heavy or relying on direct and social, and how their audience profile compares. That kind of top-down market context isn’t something Semrush gives you — and it genuinely shapes how I prioritize the SEO work that follows.

The way I see it: Similarweb tells me the competitive landscape. Semrush tells me exactly how to win in it.

Where Each Tool Falls Short

Honesty matters here because both tools have real limitations.

Semrush limitations worth knowing:

• Traffic estimates miss non-search channels almost entirely
• Backlink data, while large, can sometimes lag fresh link acquisitions
• The Semrush One AI visibility features are genuinely new — the dataset is still maturing compared to the depth of their organic search data
• It can overestimate traffic for pages ranking for highly seasonal keywords if the snapshot timing isn’t aligned

Similarweb limitations worth knowing:

• Smaller sites (under ~50K monthly visitors) get unreliable estimates — panel data is too thin at that scale
• SEO-specific intelligence (keyword-level data, ranking positions) is less granular than Semrush, even in higher tiers
• The pricing structure can be complex — their entry-level Web Intelligence plan at $125/mo (billed annually) gives you Competitive Intelligence but no SEO or AEO tools; those start at $333/mo annually
• Enterprise/custom features require sales calls rather than self-serve signup

The Pricing Reality

Since pricing often influences which tool someone ends up using, here’s what you’re looking at:

Semrush SEO Classic Plans

The traditional Semrush plans remain the most popular entry point for SEO professionals:

• Pro: $117.33/mo (billed annually) — 5 websites, 500 keywords tracked daily, keyword research and competitor tools, MCP access
• Guru: $208.33/mo (billed annually) — 15 websites, 1,500 keywords daily, historical data, content optimization, keyword cannibalization analysis
• Business: $416.66/mo (billed annually) — 40 websites, 5,000 keywords daily, API access, Share of Voice, migration from third-party tools

Pro and Guru include a 7-day free trial. Business requires a custom signup.

Semrush One (Introductory Pricing)

The newer Semrush One plans bundle traditional SEO with AI visibility tracking:

• Starter: $165.17/mo (annually) — 5 websites, 500 keywords, 1 domain for AI brand performance, 50 prompts daily, 300 AI visibility reports/day
• Pro+: $248.17/mo (annually) — 15 websites, 1,500 keywords, 100 prompts daily, historical SEO data
• Advanced: $455.67/mo (annually) — 40 websites, 5,000 keywords, 200 prompts daily, SEO share of voice, expanded API access

Starter and Pro+ offer a free trial. Advanced requires a subscription or a custom plan.

You can explore Semrush Pro vs Guru if you’re deciding between the classic tiers, or check the current Semrush plan breakdown for a full comparison.

Similarweb Web Intelligence Plans

Similarweb’s self-serve Web Intelligence tiers for entrepreneurs:

• Competitive Intelligence: $125/mo (annually) or $199/mo (monthly) — website performance, traffic & engagement, customer demographics, marketing channel overview, 3 months historical data
• Competitive Intel & SEO & AEO: $333/mo (annually) or $399/mo (monthly) — adds organic search, keyword research, rank tracking, site audit, AI brand visibility, 150 tracked prompts, 6 months historical data
• Competitive Intel, SEO & AEO & Ads: $542/mo (annually) or $649/mo (monthly) — adds display advertising, PPC marketing, publisher analysis, ad spend data

All three tiers include a free trial option.

Semrush vs Similarweb: Pricing at a Glance

So Which One Should You Actually Use?

The short answer: probably both, for different things. But if you have to pick one, the decision is simpler than it looks.

Use Semrush if:

• Your primary goal is SEO — ranking content, researching keywords, auditing your site, and building links
• You want actionable data at the keyword and page level
• You’re tracking AI search visibility as it relates to your own domain
• You’re a solo creator, agency, or SEO team with a search-first workflow

If you haven’t tried it yet, the 7-day Semrush free trial is the cleanest way to evaluate it without committing. You can also explore how to use Semrush for free beyond the trial to understand what the free-tier tools actually offer.

Use Similarweb if:

• Your primary goal is market-level competitive intelligence — understanding industry dynamics, tracking competitor traffic share, or analyzing audience behavior
• You’re in retail, eCommerce, or sales strategy where total traffic and channel mix matter more than keyword rankings
• You need to benchmark a company’s digital performance for investment, partnership, or acquisition research

Use both if:

• You’re an agency or in-house team running multi-channel campaigns where you need keyword-level SEO data and full-funnel traffic intelligence simultaneously
• You’re doing competitive research where you need to know both “what are they ranking for” and “how much of their growth is coming from non-search channels.”