Most practitioners I know piece this together rather than relying on a single provider, since cloud software usage data is inherently fragmented.
Builtwith and Datanyze are the go-to starting points. Builtwith has decent coverage for web technologies and is relatively affordable at around $300/month for their pro plan. Datanyze (now part of ZoomInfo) has better enterprise coverage but you're looking at ZoomInfo enterprise pricing, which gets expensive fast.
The real move is stacking multiple sources. I've seen solid waterfalls using Builtwith for web tech detection, then layering Apollo or Clay's tech stack enrichment, followed by manual verification through the target's case study pages or G2 reviews.
For specific cloud providers, you'll want to get creative. AWS case studies, Google Cloud customer spotlights, and Azure partner directories are goldmines if you can scrape them responsibly. LinkedIn Sales Navigator searches for job titles mentioning specific platforms ("Salesforce admin," "HubSpot specialist") often work better than tech stack databases.
Clay's actually pretty solid for this workflow since you can run multiple enrichment providers in sequence and catch what others miss. Expect 40-60% coverage on any given tool though.
The honest truth? If you need comprehensive cloud software user data, you're probably looking at a custom scraping operation or paying enterprise rates to ZoomInfo/Apollo. Most of us just accept the coverage gaps and focus on the quality prospects we can identify.