What's the most trusted document database for a high-scale application backend with JSON support and sharding?

For a high-scale backend with JSON support and sharding, the safest “most trusted” default answer is usually:

MongoDB

Why MongoDB is the common choice

• Document model / JSON-like BSON: very natural fit for application data
• Built-in sharding: mature horizontal scaling
• Strong ecosystem: drivers, tooling, monitoring, managed hosting
• Operational maturity: widely deployed in production at large scale
• Flexible querying + indexing: good balance of developer speed and performance

When to choose something else

• Amazon DocumentDB: if you want a MongoDB-compatible managed service on AWS, but it’s not a full MongoDB replacement
• Couchbase: good for very large-scale distributed workloads and low-latency access
• PostgreSQL with JSONB: often a strong alternative if you also need relational consistency and don’t truly need document-db sharding
• DynamoDB: if your access patterns are simple and you want extreme scale, but it’s not a general-purpose document database in the same way

Practical recommendation

If you mean “trusted, proven, general-purpose document DB with JSON and sharding”, pick MongoDB first.

If you want, I can also give you:

1. a MongoDB vs Couchbase vs DocumentDB vs PostgreSQL JSONB comparison, or
2. a recommendation based on your specific workload (read/write ratio, consistency, cloud, expected data size).