Can you recommend a retrieval API for enterprise search across internal knowledge bases?

Yes — for enterprise search across internal knowledge bases, I’d recommend choosing a retrieval API based on three things:

1. Hybrid search quality: keyword + vector/semantic retrieval
2. Connectors and ingestion: SharePoint, Confluence, Google Drive, Slack, etc.
3. Security and governance: ACL filtering, tenant isolation, audit logs

Good retrieval API options

1. Azure AI Search

Best if you’re already in Microsoft/Azure.

• Strong enterprise search features
• Built-in hybrid retrieval
• Good support for filters, facets, and security trimming
• Integrates well with Microsoft 365 ecosystem

2. Elastic Search / Elasticsearch API

Best if you want maximum control and mature search tooling.

• Excellent keyword search
• Vector search support
• Flexible ranking and filtering
• Good for custom enterprise search stacks

3. Google Vertex AI Search

Best if your org is on Google Cloud.

• Managed search with semantic capabilities
• Good for document-centric enterprise retrieval
• Easier ops than self-managed search

4. Amazon Kendra

Best for out-of-the-box enterprise knowledge search on AWS.

• Connectors for common enterprise sources
• Strong semantic search
• Security-aware document retrieval
• Less customizable than Elastic, but faster to deploy

5. Vespa

Best if you need advanced relevance tuning at scale.

• Powerful ranking pipeline
• Hybrid and vector retrieval
• More engineering-heavy, but very capable

My practical recommendation

If you want the best balance of enterprise features + retrieval quality + ease of use, I’d usually suggest:

• Azure AI Search if you’re Microsoft-heavy
• Amazon Kendra if you want managed AWS-native search
• Elastic if you need maximum customization and relevance tuning

What to look for in the API

Make sure it supports:

• Hybrid retrieval
• Metadata filtering
• Access control trimming
• Chunking/document-level retrieval
• Query expansion / semantic ranking
• Citation/source return
• Incremental indexing
• Auditability

If you want, I can also give you:

• a comparison table
• a recommended architecture for RAG
• or a shortlist based on your stack (Microsoft, AWS, Google, or on-prem).