The problem appending solves
Most B2B databases are incomplete in predictable ways. A list built from event badge scans has names and companies but rarely phone numbers. A CRM inherited from a previous team is missing job titles or has emails that bounce. Data appending targets exactly the fields that are missing or wrong, without touching the parts of the record that are already correct.
The alternative, manually researching missing fields one contact at a time, doesn't scale past a few dozen records. Appending applies the same matching process across a database of any size, whether that's 500 records or 500,000.
Four ways to append your data
- Email appending — add verified email addresses to records that only have a name, company, or postal address
- Phone appending — add responsive, verified phone numbers for outreach and telemarketing, at 99.9% accuracy
- Social media appending — match public social profiles to existing contact records
- Reverse appending — start from one data point and fill in the rest
Each of these has its own dedicated page with the full process and FAQ, since "append my data" usually means one specific field, not all of them at once: email appending, phone appending, or reverse appending. This page covers the shared process and the parts of appending that apply regardless of which field you need filled.
How it works
Send your database
Upload the file you want appended, missing fields and all, along with which fields you specifically need filled.
We check it
Our data team checks it against internal databases for matches, using whatever identifiers your records already contain.
Fields are added
Specific contact information is added per your request, verified before it's written into the final file.
You get the file
Receive a precise, ready-to-use database on your target contacts, typically within 4 to 5 business days.
Who uses data appending
A sales operations manager inherits a CRM with thousands of contacts missing phone numbers, and needs the gaps filled before the team can start a calling campaign.
An events team collects business cards and badge scans at a trade show, names and companies only, and needs emails and phone numbers appended before the leads can be worked.
A data operations analyst is standardizing a merged database after an acquisition, where two systems used different fields and neither is complete on its own.
Why teams choose Data Mappers for appending
- Segmented, ready-to-use master lists instead of raw exports
- Active, responsive, current email addresses, not stale records
- Additional detail available on request: company names, fax, sales data
- Coverage across the USA and international markets, 175+ countries in total
- Served industries include financial services, technology, marketing, healthcare, travel, and real estate
- Pricing based only on the data you actually request
Before you commit
- Cost concerns: you're quoted on the specific fields you need, not a flat per-record database fee.
- Accuracy concerns: 95%+ overall accuracy with real-time email verification, 99.9% specifically on phone appending.
- Compliance concerns: data is 100% verified and permission-passed, compiled in line with GDPR and CAN-SPAM.
- Bounce risk: hard bounces and disconnected numbers are covered by replacement or refund.
Frequently asked questions
What types of data appending do you provide?
Email appending, phone appending, social media appending, and reverse appending, plus postal address and full contact appending.
Where does the appended data come from?
Data Mappers gathers structured and unstructured data from trustworthy online and offline sources, including subscriptions, business cards, government records, corporate directories, and trade shows and events, combined with AI matching and manual review.
What does data appending cost?
Pricing depends on database size and the specific fields requested. Upload your list for an accurate estimate before proceeding.
What is email appending specifically?
Email appending is the process of adding email addresses to an existing client list by matching known details like name and company against a verified database. See our dedicated email appending page for more detail.
How accurate is appended data?
Data Mappers offers 95%+ accuracy with real-time email verification, and phone appending specifically runs at a 99.9% accuracy rate.
What if some of the appended data bounces or is wrong?
Hard bounces and disconnected numbers are covered. Contact Data Mappers for a replacement or refund on the affected portion of your list.
Can I append just one field, like phone numbers, without the rest?
Yes. Pricing is based only on the specific fields you request, so you can append a single field or several at once.