
ZoomInfo
Lusha
Hunter.io
Instantly.ai
Clearbit
lemlist
Snov.io
Apollo’s predictive prospecting, sales engagement, and actionable analytics help the teams to reach its full revenue potential.

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Which is more popular?
Based on our record, Apollo.io seems to be more popular. It has been mentioned 69 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | apollo.io | opalstack.com |
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| Company | Startup from the United States | — |
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What each product offers, as listed by its team.


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Overall verdict
Why this product is good
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Overall verdict
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Free software to find email addresses - apollo.io review
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How often each product is chosen within a category, 0–100% relative to the other.


Share your experience with using Apollo.io and Opalstack. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


What is the best AI prospecting tool for B2B sales in 2026? The best tool depends on your team's specific situation. toflow.ai is a strong fit for multi-channel outreach across email, LinkedIn, and WhatsApp, and is...
We use Apollo with our Sales and BDR team to manage our cold outreach. The strength of the platform is the sequences and cadences that you can set up. Compared to other tools we have used in the past like Salesloft...
FAQWhat’s better than Apollo.io?What Apollo.io competitors are better for lead generation? What is Apollo.io used for?
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Recommendations tracked on public social media and blogs since March 2021.


Personal email domains destroy this. Clearbit's Enrichment API returns a null company when it hits gmail.com. Apollo routes personal domains straight to a consumer bucket and skips B2B fields entirely. Even PDL's /person/enrich endpoint... - Source: dev.to / 4 months ago
A few things worth flagging: PDL beats Clearbit's historical rates for US and Western European companies, but drops to ~52% match rate for Japan and South Korea specifically. Apollo underperforms on raw company matching but returns... - Source: dev.to / 4 months ago
One thing comparison guides consistently get wrong: Clay is not an enrichment API. It's a waterfall orchestration tool that calls People Data Labs, Apollo, Clearbit, and others in sequence for you. It's useful, but it adds 2–8 seconds of... - Source: dev.to / 4 months ago
Tracking Opalstack since Sep 2023.
When comparing Apollo.io and Opalstack, you can also consider the following products.

ZoomInfo is a B2B database providing detailed business information on people and companies.
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Find all the email addresses related to a domain
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Build your own infinitely scalable cold email outreach system with Instantly.
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The prospecting tool to automate multichannel outreach & actually get replies.
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