What is Data Append?
Picture this: You’ve just wrapped up a massive trade show. Your booth was packed, you collected hundreds of business cards, and your sales team is pumped. But when you get back to the office and start entering contacts into your CRM, you realize most people only scribbled down their name and company on the badge scanner. No email addresses, no phone numbers, no job titles.
This is exactly where data append comes in.
Data append is the process of taking what you already have about someone—like their first name, last name, and company—and filling in the missing pieces. Think of it as playing detective with your database. You provide the clues you know, and a data append service searches through massive databases to find what’s missing: the email address, direct phone number, job title, or even LinkedIn profile.
Here’s the crucial part to understand: Data append is about enhancing existing records, not building lists from scratch. You need to start with something—at minimum, a name and company. The service then matches your partial data against their databases to complete the picture.
Let’s say you have Sarah Martinez who works at Acme Corp. A data append service can potentially find sarah.martinez@acmecorp.com, her direct dial number (555-0123), her title (Director of Marketing), and maybe even her LinkedIn profile. Pretty powerful, right?
Types of Data Append Services
Email Append: Finding the Digital Address
Email append is probably the most popular type of data appending, and for good reason. In B2B sales and marketing, email is still king. You might have someone’s name from a webinar registration where they used their personal Gmail account, or from a business card that didn’t include email. Email append bridges that gap.
Here’s what you need to make it work: a first name, last name, and company name (or even better, the company domain). The service then searches its databases to find the most likely business email address for that person.
Now, let’s talk reality. You’re not going to get 100% match rates. Based on what we’ve seen across hundreds of projects, here’s what to expect:
If you have a high-quality list where the names are recent and accurate, you might see match rates of 50-70%. That’s the best-case scenario. More typically, with a list that has some outdated information or companies where people have moved around, you’re looking at 40-55%. And if you’re working with an old list where there have been lots of job changes, expect 20-40% at best.
Real-world example: A client came to us with 5,000 trade show leads from the past year. They had names and companies but needed emails. After running an email append, we matched 2,750 records—a 55% match rate. Not perfect, but it turned an unusable list into 2,750 potential outreach opportunities.
Phone Append: Getting the Direct Line
Phone append adds phone numbers to your records, but here’s where it gets interesting: not all phone numbers are created equal. You could get a direct dial to someone’s desk phone, their mobile number, or just the company’s main switchboard number.
Direct dials are gold for outreach—you’re calling straight to their desk. Mobile numbers are even better for reaching executives who are constantly on the move. But main line numbers? Those are less valuable because you still need to navigate through reception.
Match rates for phone append are generally lower than email. You’re looking at 30-50% for direct dials, 20-40% for mobile numbers, and 40-60% if you’re willing to accept any type of phone number (including those less useful main lines).
One sales team we worked with needed to build out their cold calling campaigns. They had 10,000 contacts with emails but no phone numbers. After phone append, they got direct dials for 3,800 people and mobiles for about 2,200. It wasn’t perfect coverage, but it gave them a solid foundation for multi-channel outreach.
Firmographic Append: Understanding the Company
Firmographic append is all about adding company information to your contact records. This is incredibly useful for lead scoring, segmentation, and determining if a company fits your ideal customer profile.
With just a company name or domain, you can get back industry codes, employee count, revenue ranges, headquarters location, and company type (public, private, non-profit, etc.). Match rates here are typically higher—70-90% for recognizable companies—because company data changes less frequently than contact information.
Imagine you’re trying to prioritize which leads to call first. With firmographic data, you can instantly segment companies with 500+ employees in the manufacturing industry with annual revenue over 50 million dollars. That’s the power of good firmographic appending.
Contact Append: Finding More People at Target Accounts
Contact append is a bit different. Instead of filling in gaps about people you know, it’s about finding additional people at companies you’re already targeting. You provide a company name or domain, and the service returns new contacts based on the titles you specify.
This is essential for account-based sales. Let’s say you’re already talking to someone in the IT department at a company, but you know you need to get the CFO and VP of Operations involved to close the deal. Contact append helps you find those additional stakeholders without manually hunting through LinkedIn for hours.
Social Append: Connecting the Digital Dots
Social append adds social media profiles—primarily LinkedIn URLs—to your contact records. Match rates for LinkedIn append run about 60-80% for business professionals, which makes sense given how prevalent LinkedIn is in B2B circles.
Why would you want this? Sales reps can quickly research prospects before calls, marketing can build lookalike audiences, and you can verify that the person you think you’re contacting actually exists and works where you think they do.
How Data Append Actually Works
Let’s walk through a typical data append project from start to finish so you know what to expect.
First, you need to prepare your list. This isn’t just uploading a messy spreadsheet and hoping for the best. You’ll want to clean up formatting, standardize how names are entered (all caps vs. proper case), remove obviously bad data (like test@test.com or John Doe entries), and deduplicate so you’re not paying to append the same record twice.
Next, you submit your list to the provider. This might be through file upload, API integration, or sometimes even sending them a CSV via email, depending on the provider. You’ll specify which fields you need appended and can often set quality thresholds—for instance, only return emails with a confidence score above 80%.
Then comes the matching process, which happens on the provider’s end. They’re searching through their databases, matching your partial information against multiple sources, and applying confidence scores to each match. Good providers don’t just check one database—they verify across multiple sources to ensure accuracy.
When you get your results back, you’ll see your original records with the newly appended data, confidence scores for each match, and flags for records that couldn’t be matched. This is where the real work begins.
You absolutely must verify the results before using them. For emails, run them through an email verification tool. For phone numbers, have someone on your team sample dial 20-50 numbers to check accuracy. Spot check 50 random records against LinkedIn to verify job titles and companies. This verification step is not optional if you want to maintain good sender reputation and avoid wasting your team’s time.
Finally, when you’re confident in the data quality, you import into your CRM. But don’t just overwrite existing data blindly. Tag the source as “appended” so you know where it came from, and consider setting appropriate contact preferences. Some teams even warm up appended email addresses separately from their main sending infrastructure.
Choosing the Right Data Append Provider
The market is crowded with data append providers, and they’re not all created equal. Here’s how to think about your options.
For comprehensive B2B data, providers like ZoomInfo offer the full package—emails, phones, firmographics, and more. They’re pricier but well-suited for enterprise companies that need scale and accuracy. Apollo is another solid choice that’s more affordable and popular with small to medium-sized businesses, offering good email append and enrichment capabilities.
If you need firmographic data specifically, especially for credit risk and financial analysis, Dun & Bradstreet is the gold standard. For consumer data or mixed B2B and consumer marketing, Experian offers robust options.
There are also specialized providers focused on specific append types. Hunter is excellent for email finding, Lusha has strong phone data, Clearbit offers real-time appending that’s great for enriching leads as they come in, and FullContact specializes in social profiles and identity resolution.
For self-service projects where you want to just upload a list and get results quickly, tools like Apollo, Hunter, Snov.io, and RocketReach let you do exactly that without talking to a sales rep or signing a long-term contract.
Best Practices for Data Append Projects
Here’s what we’ve learned from running countless data append projects: preparation and verification matter more than the provider you choose.
Before you start, invest time in cleaning your existing data. Standardize name formatting, remove records you know are bad, deduplicate thoroughly, and make sure company names are formatted consistently. The quality of what you put in directly impacts the match rate you’ll get out.
Set realistic expectations with stakeholders. You’re not going to match 100% of records. There will be people who’ve changed jobs, companies that have rebranded, and records that just can’t be matched. That’s normal.
Always sample first. Take 100-500 records, run them through the append process, and evaluate both the match rate and the accuracy of what you get back. This small investment can save you from spending thousands on a full list that doesn’t meet your needs.
Track everything. Know your original record count, how many matched, your match rate by field type, and your cost per match. This data helps you optimize future projects and build a business case for the investment.
After appending, the verification step is critical. For emails, use a verification service to remove invalid and risky addresses—this protects your sender reputation. For phones, sample dial to check accuracy. And always spot-check a random sample against LinkedIn or other sources to verify the data makes sense.
When importing into your CRM, be surgical. Don’t overwrite good data you already have with newly appended data. Tag records so you know the source. Consider warming up appended email addresses separately before sending high-volume campaigns. And make sure you’re respecting contact preferences and compliance requirements.
Understanding the Costs
Data append pricing varies based on the type of data and the provider, but here’s what you can generally expect.
Email append typically runs $0.05 to $0.15 per matched record. Phone append is more expensive at $0.15 to $0.50 per match, especially for direct dials and mobile numbers. Firmographic append falls in the middle at $0.10 to $0.30 per record. If you want a full profile with multiple data points, expect to pay $0.25 to over $1.00 per record.
Pricing models vary too. Per-match pricing means you only pay for successful matches—good when you’re uncertain about list quality. Per-record pricing charges for each record processed whether it matches or not, but often at a lower rate—good for high-quality lists where you expect good match rates. Subscription models charge monthly or annually and include a volume of appends, which works well for ongoing needs.
For a typical B2B database enhancement project, budget $500 to $5,000 depending on list size and data types needed.
Common Pitfalls and How to Avoid Them
Low match rates frustrate everyone. They usually stem from poor input data quality, outdated lists, or names that don’t match what’s in the provider’s database. The solution is thorough cleaning before submission and realistic expectations about what’s achievable.
Inaccurate data is the other major issue. Even when you get a match, the data might be outdated—people change jobs, phone numbers change, email addresses get deactivated. This is why verification isn’t optional. Always verify before launching campaigns.
High bounce rates with appended emails can torpedo your sender reputation fast. The solution: verify 100% of appended emails before sending anything, use reputable providers with fresh data, and run your append projects close to when you’ll actually use the data.
Compliance concerns are real. Make sure you understand regulations like GDPR and CCPA, use providers who can explain where their data comes from, and honor opt-outs immediately. Just because you can append someone’s email doesn’t always mean you should use it.
Key Takeaways
Data append is a powerful tool for enhancing your existing database, but it’s not magic. Success comes from realistic expectations, thorough preparation, and rigorous verification.
Remember that append services fill gaps—they don’t build complete lists from scratch. You need to start with something. Email append typically delivers 40-60% match rates, while phone append is lower at 30-50%. Always verify appended data before launching campaigns to protect your sender reputation and sales team’s time.
Costs generally range from $0.05 to $0.50 per matched record depending on data type, which is reasonable when you consider the alternative of manual research.
The key insight: Data append works best as part of a comprehensive data strategy, not as a standalone solution. Use it to fill specific gaps, verify what you get, and integrate it thoughtfully into your outreach programs.
Ready to Enhance Your Database?
We’ve helped hundreds of companies run successful data append projects that turn incomplete databases into actionable lead lists. If you’re sitting on a database with missing information and want expert guidance on the best approach, book a call with our team. We’ll walk you through the options and help you get the data quality you need.