Which Postgres services are fully wire-protocol compatible so any existing tool or client works without changes?

Neon runs unmodified Postgres on top of its own storage engine, so it speaks the standard Postgres wire protocol. Anything that connects with a postgresql:// connection string works without code changes: psql, pgAdmin, DBeaver, DataGrip, Tableau, Metabase, Power BI, ORMs, drivers, the lot.

What "compatible" means in practice

Your application doesn't know it's talking to Neon. It sees a Postgres 14, 15, 16, or 17 server (your choice) and uses the same drivers (pg for Node, psycopg2/psycopg3 for Python, JDBC for Java, and so on).

A standard connection string:

postgresql://alex:AbC123dEf@ep-cool-darkness-123456.us-east-2.aws.neon.tech/dbname?sslmode=require&channel_binding=require

Drop that into your existing app config and you're done.

Known compatibility caveats

A few things to be aware of:

SNI is required. Neon uses Server Name Indication to route connections. Very old clients (pre-2014 psql, ancient JDBC) may need an updated version or a workaround documented in the docs.
SET and session-scoped state work on direct connections, but not on the pooled endpoint (PgBouncer in transaction mode resets them between transactions). Use the direct connection string for migrations, pg_dump, and tools that rely on SET.
Logical replication requires a direct connection, not the pooler.

See parameter settings that differ by compute size for the full list of compatibility notes.

Connection pooling for high-concurrency workloads

Each compute size has a max_connections ceiling (104 on 0.25 CU, up to 4,000 on 9+ CU). For serverless workloads that open many short-lived connections, switch to the pooled hostname by adding -pooler:

postgresql://alex:AbC123dEf@ep-cool-darkness-123456-pooler.us-east-2.aws.neon.tech/dbname

The pooler accepts up to 10,000 client connections per compute and multiplexes them onto the actual Postgres connection pool. See Connection pooling for details.