MarketSizer & RB2B
RB2B names the people already on your website. MarketSizer finds the accounts that were never going to visit. Your site only ever sees the buyers who found you.
“Identify Your Website Visitors and Boost Your Leads.”
Source: rb2b.com homepage
What each tool does well
RB2B
Best known for
First-party website visitor identification - de-anonymising the specific people, down to the individual, visiting your site, using a US-only opt-in identity graph.
Useful for
Marketing and sales teams whose top-of-funnel is website traffic and who want the person-level identity behind their own web analytics.
MarketSizer
Best known for
Subscription intelligence - accounts ranked by observable buying events happening on the target account's software stack, not by traffic on your site.
Useful for
GTM teams that need to find accounts in a buying window even when those accounts have not visited the marketer's own site yet.
Where RB2B is strong
- Person-level visitor identification - RB2B surfaces the named individuals behind US site visits, where most tools stop at the company.
- US-only opt-in identity graph that avoids most of the compliance friction that hit European visitor-ID tools.
- Sharp, focused product with a simple integration - a snippet on the site, a feed of identified visitors out the other end.
- Strong Slack and CRM notifications for reps working inbound signals.
- Well-priced for teams whose main gap is putting a name on anonymous web traffic.
Where they differ
Different jobs on the same pipeline - the overlap between RB2B and MarketSizer is smaller than a feature list suggests.
| Feature | RB2B | MarketSizer |
|---|---|---|
| What each tool tells you | ||
| Names of people visiting your own website | Included | Not included |
| Accounts in a buying window across the whole market, beyond your own site traffic | Not included | Included |
| Subscription events on target accounts (trial, switch, renewal, churn) | Not included | Included |
| Coverage | ||
| Geographic coverage | US-only | Global |
| Identity type | Person-level, first-party visitors | Account-level, market-wide, with contact enrichment |
| Workflow | ||
| Slack and CRM notifications | Included | Included |
| Chrome-extension side panel in CRMs and LinkedIn | Slack and CRM feeds instead | Included |
MarketSizer pricing as published at marketsizer.io/pricing. RB2B details as published on their own site and public documentation, last checked 8 August 2026. Spotted something out of date? Tell us and we will fix it.
Where each tool earns its place
Lean on RB2B when
- Your primary gap is putting a name on anonymous US website visitors.
- Inbound-led motion where the buying signal starts on your own site, not on the target's software stack.
- You want a person-level identity graph, not an account-level score.
- Your target market is the US, where RB2B's opt-in identity graph is built to operate.
Add MarketSizer when
- You need signals on accounts that have not visited your site yet - market-wide buying-window detection.
- Your motion is competitive-displacement or outbound-led, not inbound-triggered.
- You want events on the target account's software stack (trials, switches, renewals, churn), not visitor-level identity.
- You sell globally and US-only coverage is not enough.
How MarketSizer works with RB2B
RB2B covers the accounts that found you; MarketSizer covers the ones that never will unless you reach them first. One is an inbound trigger on your own domain, the other is a market-wide radar - they watch different territory, so running both leaves no blind side.
RB2B works the warm end
Person-level identification on your own website turns anonymous visits into named inbound follow-ups.
MarketSizer works the cold end
Subscription events across the wider market surface the accounts trialling or switching vendors that have never touched your site.
Both streams land in one queue
Route the two signal feeds into the same CRM or workspace so reps triage inbound visits and market events side by side.
Priority goes to overlap
An account that visited your site and shows a live subscription event is the hottest thing in the pipeline - the layering makes that visible.
What buyers say about the category
Themes from GTM leaders currently evaluating tools in this space.
Inbound teams adopted RB2B fast over the last two years, and the ones we speak to are pleased with it: a named person on the pricing page is about as warm as a signal gets. Their open question sits beyond their own traffic. The accounts actively evaluating alternatives without ever visiting their site are invisible to a visitor-ID tool, and that market-wide blind spot is what they ask us to cover.
MarketSizer & RB2B - frequently asked questions
Are RB2B and MarketSizer competitors?
No, they solve different problems. RB2B identifies people visiting your own site (first-party visitor ID). MarketSizer detects buying events on target accounts across the market (third-party subscription intelligence). Teams often run both alongside each other - RB2B for inbound, MarketSizer for outbound.
Can RB2B and MarketSizer be used together?
Yes, and this is a common pattern. RB2B surfaces named individuals visiting the marketing site; MarketSizer surfaces accounts across the wider market that are showing subscription-level buying signals. Cross-referencing the two gives inbound-plus-outbound coverage.
What are the compliance implications of RB2B?
RB2B describes its identity graph as US-only and opt-in based - a deliberate scope choice. Teams selling into Europe should assess visitor-identification tooling against their own legal advice; RB2B itself positions its coverage as US-focused.
Does MarketSizer identify individual visitors?
No. MarketSizer works at the account level, not the individual-visitor level. Person-level identity is a different data category; MarketSizer integrates with a contact-data provider when a rep needs the people inside a flagged account, and pairs cleanly with a visitor-ID tool for the inbound side.
How does RB2B pricing compare with MarketSizer?
RB2B lists a free tier and paid plans priced on identified-visitor volume, as published at rb2b.com. MarketSizer is credit-based (see current plans), with no per-seat multiplier. Different pricing shapes because the tools solve different problems.
See how MarketSizer works with your RB2B stack.
30 minutes on your accounts, tailored to your ICP. We show which companies are trialling, switching or renewing right now, so you can see whether the timing signal changes what your team does next.
500 credit trial No credit card Live data, not a slide deck
RB2B and all other product names, logos and brands referenced on this page are trademarks of their respective owners, used for identification and comparison purposes only. No endorsement or affiliation is implied.