Comparison
Let's be clear about the split, because these tools do not do the same job. DemandTools and Cloudingo are powerful paid tools that run inside Salesforce, deduping, merging, and mass-updating records that are already in the org. Sift is free and cleans the file before it ever enters Salesforce. If you're paying about $5k a year to dedupe inside your org, the cheapest fix is to stop importing dirty lists in the first place.
Clean your list in Sift, free →
Both are Salesforce-native platforms, and for in-org work they earn their keep. They do mass dedupe and merge across records already in the database, run scheduled jobs so duplicates get caught on an ongoing basis, and handle mass updates across an existing org at scale. On Reddit, Cloudingo is the most-recommended Salesforce dedupe tool, and DemandTools is a common second name in the same threads. This capability is why they carry subscription pricing.
As documented: DemandTools runs roughly $11 per Salesforce license per month (a median around $4,825 a year at 50 seats, per Vendr), and its move to org-based pricing drew loud anger from long-time customers. Cloudingo is commonly cited around $2,500 to $6,000 a year. Those are the numbers to weigh against how much of the mess is actually already in your org versus how much arrives with every new import.
Sift sits one step earlier, before the list becomes an org problem. It's free, it runs before import, and nothing is uploaded: no API, no Salesforce connection, no credentials. You drop in a CSV or Excel file, Sift cleans and dedupes the list in your browser, and you export a file with far fewer duplicates ever reaching the org. Every duplicate you merge on the file is one you never have to pay a per-seat tool to catch later.
The honest workflow: use Sift to keep new lists clean before they land, and reach for a Salesforce-native tool when the org itself is what needs cleaning.