Duplicate Checker API

Overview

The Duplicate Checker API lets a lead vendor check whether a hashed phone number or email address already exists as a lead for a company before sending that lead. It is a pre-filter gate only — calling this API never creates or modifies a lead. Raw PII never crosses the wire; you send an MD5 hash of the canonicalized value, never the phone number or email itself.

Base URL: https://duplicatecheck.revenuescale.com (also reachable at https://api.revenuescale.com). Endpoint path is the same on both hosts:

POST /api/v1/duplicate-check

Authentication

Each lead source (vendor) is issued its own API token. The company you send leads to provides you with a token for your feed — reach out to your contact there if you don't have one yet. The token is shown only once when it is created and cannot be retrieved afterward, so store it securely; if it is ever lost or compromised, ask the company to issue a replacement.

Send the token either as a header (preferred) or in the request body:

• X-Api-Key: <token> header, or
• "key": "<token>" field in the JSON body

If both are present, the X-Api-Key header takes precedence.

Canonicalization & hashing rules

Hashes must be computed exactly as described below, or they will never match. This is a public contract — the rules do not change without a coordinated vendor-facing rollout.

Example: (512) 555-1212 and +1-512-555-1212 both canonicalize to 5125551212 before hashing. Jane@Example.com canonicalizes to jane@example.com before hashing.

Request

POST /api/v1/duplicate-check — JSON body:

Response

200 OK with one of:

The match spans every lead source the company has, not just yours — a lead ingested through a different vendor is still flagged as a duplicate.

Lookback window

A match only counts as a duplicate when the company's existing lead was created or last updated within the lookback window — 30 days by default. If the most recent matching lead is older than the window, the contact is treated as new and the response is accepted. In other words, a lead the company hasn't worked in more than the window is fair to send again, even though they had it at some point.

Example (default 30 days): a contact the company last touched 12 days ago returns duplicate; the same contact last touched 45 days ago returns accepted.

The window length is configurable and may differ from the 30-day default from one company to the next. If you need a specific company's window, ask your contact there. The duplicate / accepted behavior is the same regardless of the number.

Errors

Examples

Phone

PHONE="(512) 555-1212"
HASH=$(python3 -c "
import hashlib, re
digits = re.sub(r'\D', '', '$PHONE')
if len(digits) == 11 and digits.startswith('1'):
    digits = digits[1:]
print(hashlib.md5(digits.encode()).hexdigest())
")

curl -X POST https://duplicatecheck.revenuescale.com/api/v1/duplicate-check \
  -H "Content-Type: application/json" \
  -H "X-Api-Key: dc_live_your_token_here" \
  -d "{\"company\": \"acme-co\", \"type\": \"phone\", \"hash\": \"$HASH\"}"

Email

EMAIL="Jane@Example.com"
HASH=$(python3 -c "print(__import__('hashlib').md5('$EMAIL'.strip().lower().encode()).hexdigest())")

curl -X POST https://duplicatecheck.revenuescale.com/api/v1/duplicate-check \
  -H "Content-Type: application/json" \
  -H "X-Api-Key: dc_live_your_token_here" \
  -d "{\"company\": \"acme-co\", \"type\": \"email\", \"hash\": \"$HASH\"}"

Both return {"result": "duplicate"} or {"result": "accepted"}.

Security note