B2B contact data is the information you need to reach someone at a business: their name, title, company, work email, and sometimes a direct phone number. Every outbound campaign starts with it, and the source you pick shapes how many of your emails reach a real person.
Apollo, ZoomInfo, and Clay come up in almost every conversation about lead lists. They aren’t three versions of the same thing. Two of them are databases. The third is a tool that pulls from many databases at once. Here’s how they compare, and how we use them together.
Why every contact database goes stale
Before comparing sources, it helps to know why no source is perfect. Contact data decays constantly:
- People change jobs. When someone leaves, their old email stops working, but it can sit in a database for months.
- Companies change their email setup. A new domain or a new mail provider can make old addresses invalid overnight.
- Some servers accept everything. Catch-all mail servers say yes to any address, so a database can’t confirm whether a specific person’s email is real.
That’s why teams that pay for premium data still hit dead ends. The fix isn’t only a better database. It’s checking the data right before you use it.
Paying for ZoomInfo and still hitting dead ends? We clean and refresh the list you already have before anything sends: verified emails, replacements for people who left, and a reason to reach out now. Talk to us about your list →
Apollo
Apollo is a self-serve B2B database with built-in prospecting tools. You can sign up, filter by industry, company size, location, and title, and export contacts the same day.
- Good at: getting started quickly and cheaply, with strong filters for building a starting list.
- Weaker at: accuracy varies by industry and company size, so expect a meaningful share of contacts to fail verification.
- Best for: small teams and agencies building their first lists, or anyone who wants a starting point to enrich elsewhere.
ZoomInfo
ZoomInfo is an enterprise-grade B2B database. It’s generally known for deeper coverage at mid-size and large companies, direct phone numbers, and extra data like org charts and buying intent.
- Good at: coverage and depth, especially for larger companies and phone outreach.
- Weaker at: cost and commitment. It’s usually sold on annual contracts priced for sales teams, and it still goes stale like any database.
- Watch for: license terms. ZoomInfo contracts can limit how you export data or share it with other tools and vendors, so read yours before moving data elsewhere.
- Best for: established sales teams with steady volume and a budget for it.
Clay
Clay isn’t a database. It’s a spreadsheet where each column can run a lookup. You bring a list of companies or contacts, and Clay can:
- Search several email providers in a row until one finds an address, which fills gaps that any single database leaves.
- Verify each email before it goes into your sending tool.
- Pull live signals, such as whether a company is hiring right now.
- Research each company with AI to write a first line based on what they actually do.
The tradeoff is that Clay runs on credits, so every lookup has a cost, and it takes some setup to learn. It works best on top of a starting list, not as a replacement for one.
Side by side
| Apollo | ZoomInfo | Clay | |
|---|---|---|---|
| What it is | Self-serve database | Enterprise database | Enrichment tool that pulls from many sources |
| How you pay | Monthly plans, low entry cost | Annual contract | Credits per lookup |
| Main strength | Fast, affordable starting lists | Coverage and depth at larger companies | Fresh, verified, enriched data |
| Main weakness | Accuracy varies | Cost and contract limits | Learning curve and credit costs |
Plans and pricing change often, so check each tool’s current pricing before you commit.
Which should you use?
- Just starting out: Apollo for the list, plus an email verifier before you send.
- Already paying for ZoomInfo: keep using it for the starting list, and add verification so stale contacts get caught before they bounce.
- Want better replies, not just more contacts: add Clay on top of either one for hiring signals, email waterfalls, and personal first lines.
How we use them
For Next Reply campaigns, the database is only step one. We pull a starting list from Apollo or from the client’s own ZoomInfo account when their license allows it. Then we verify every email, find replacements for people who have left, add a reason to reach out now, and check which mail provider each company uses. Only verified contacts with a reason to hear from you make it into a campaign.
If you want to see the full list-building process, read how to build a B2B lead list that doesn’t bounce. To check which mail provider your prospects use, try our free MX checker.
Related guides: what makes a B2B email list usable and where to buy B2B leads. If you would rather hand off the data and the outreach, see outsourced lead generation and our B2B lead generation services.
Frequently asked questions
Is ZoomInfo better than Apollo?
ZoomInfo generally has deeper coverage at mid-size and large companies and more phone data. Apollo is cheaper and self-serve. Neither is always accurate, so verifying the list matters more than which one you start from.
Is Clay a contact database?
No. Clay is an enrichment tool. It pulls from many data providers, verifies what it finds, and adds signals and research. Most teams use it on top of a starting list from a database like Apollo or ZoomInfo.
Why do emails from a paid database still bounce?
People change jobs and companies change their email setup faster than any database can update. Verifying each address right before you send catches most of these before they bounce.
Can you use ZoomInfo data in other tools?
It depends on your contract. ZoomInfo licenses can limit exporting data or sharing it with other tools and vendors, so check your terms or ask your account rep before moving data elsewhere.
Tired of dead ends?
We build, verify, and refresh the list for every campaign, and you approve it before anything sends. Tell us who you want to reach and we’ll show you what a clean list looks like for your market.