Addax

Addax copies data between databases, files and warehouses: MySQL to ClickHouse, Postgres to HDFS, Kafka to Redis, Excel to MongoDB. You write one JSON file naming a reader and a writer, run it, and the rows move. It's the maintained fork of Alibaba's DataX, which hasn't tagged a release since September 2023, and it's free under Apache 2.0.

It's a Java 17 command-line tool with a Docker image and an install script, no cluster required. A server mode takes jobs over HTTP, and a separate web console, Addax Admin, handles scheduling and monitoring. Built-in transformers cover masking, filtering and type conversion, with Groovy for custom logic.

No paid tier. Solo, small teams, larger teams: all free. You pay in time writing and scheduling jobs. It shines where your data lives in the Hadoop stack (Hive, HDFS, Kudu) or in warehouses like Doris, StarRocks and ClickHouse.

The catch: this is batch copying, not change data capture. The plugin list has no binlog or WAL reader, so for streaming every change, look at Debezium. One person writes nearly all the code, the docs default to Chinese (English is there), and the latest release carried nine breaking changes. Read the notes before upgrading.