Enterprise AI search and assistant platform founded in 2019 by ex-Google search engineers including Arvind Jain. Glean indexes everything a company runs on — Slack, Google Drive, Jira, Salesforce — and becomes the internal ChatGPT for the org. Raised at multi-billion-dollar valuations in 2024–2025. Relevant as a reference for the "enterprise knowledge layer" category that sits adjacent to both FeatureOS (product knowledge) and SupportWire (support knowledge).