# Protocols

> The wire protocols GreptimeDB speaks, for both writing and querying, and where each protocol's ingestion guide lives.

# Protocols

GreptimeDB speaks several wire protocols. They fall into two groups.

**Connection protocols** carry both writes and queries: the [HTTP API](http.md), [MySQL](mysql.md), and [PostgreSQL](postgresql.md). These pages document endpoints, authentication, and protocol-specific options. [gRPC](grpc.md) belongs here by transport but carries writes only — there is no gRPC query interface.

**Ingestion protocols** accept writes from a system that already speaks them — InfluxDB line protocol, OpenTelemetry, Loki, Elasticsearch, Splunk, and OpenTSDB. The pages here cover protocol-level details; the configuration for each source is in [Ingest Data](/user-guide/ingest-data/overview.md).

- [Elasticsearch](elasticsearch.md) — What GreptimeDB implements of the Elasticsearch protocol — the _bulk API for writes only — and where the ingestion guide lives.
- [gRPC](grpc.md) — Overview of using gRPC SDKs for efficient and high-performance data ingestion in GreptimeDB.
- [HTTP API](http.md) — Guide on using HTTP APIs to interact with GreptimeDB, including authentication, timeout settings, health checks, configuration, and SQL queries.
- [InfluxDB Line Protocol](influxdb-line-protocol.md) — Instructions on ingesting data to GreptimeDB using InfluxDB Line Protocol and using ping and health APIs.
- [Loki](loki.md) — What GreptimeDB implements of the Loki protocol — the Push API for writes only — and where the ingestion guide lives.
- [MySQL](mysql.md) — Guide on connecting to GreptimeDB using MySQL, managing tables, ingesting and querying data, and handling time zones.
- [OpenTelemetry (OTLP)](opentelemetry.md) — Consume OpenTelemetry metrics, logs, and traces natively via OTLP/HTTP protocol
- [OpenTSDB](opentsdb.md) — What GreptimeDB implements of the OpenTSDB protocol — the /api/put endpoint for writes only — and where the ingestion guide lives.
- [PostgreSQL](postgresql.md) — Guide on connecting to GreptimeDB using PostgreSQL, managing tables, ingesting and querying data, and handling time zones.
- [Splunk](splunk.md) — What GreptimeDB implements of the Splunk HEC protocol, which endpoints exist, and what is deliberately not implemented.