Extract, Transform, and Load (ETL) is a data warehousing process that uses batch processing to help business users analyze and report on data relevant to their business focus and goals. ETL process basically pulls data out of the source, makes changes according to requirements, and then loads the transformed data into a database or BI platform to provide better business insights.

Open source ETL tools can be a low-cost alternative to commercial packaged ETL solutions, especially if you have a low budget, you don’t have enough time to build a custom solution or your data analysis project is not too big.

If used appropriately, and knowing their limitations, today’s free ETL tools can be solid components in an ETL pipeline.

List of some of the most popular open source and affordable ETL tools for small-budget projects

Talend Open Studio

This version is offered for Data Integration with limited-functionality open source (Apache license) version of its Data Management Platform and
provides software to integrate, cleanse, mask and profile data. It offers connectors for various RDBMS, SaaS, packaged apps, and technologies.

Talend Open Studio works both on Windows and Mac environment.

The full version costs are around $1,170/user monthly or $12,000 annually.

Apache NiFi

The Apache NiFi allows to automate and manage the flow of information between systems, and its design model makes NiFi a very effective platform for building powerful and scalable dataflows. Its fundamental design concepts are related to the central ideas of Flow Based Programming. The main features of this project include a highly configurable web-based user interface, data provenance, extensibility, and security (options for SSL, SSH, HTTPS, and so on). This open source solution is not limited.

Apatar

Apatar is an open source data integration and ETL tool; it comes with a visual interface that can reduce R&D costs, improve data integration efficiency and minimize the impact of system changes. Written in Java and with Unicode-compliant functionality, it can be used to integrate data across teams, populate DWH, and schedule and maintain little or no code when connected to other systems.

Microsoft SSIS

If your company is using Microsoft SQL Server for database needs, you will likely find that the software’s integration services (SSIS) are adequate to meet your needs. That’s because it integrates easily with other Microsoft products and offers data quality and master data management features as well as data integration capabilities.

SSIS is a platform for building enterprise-level data integration and data transformations solutions. It can extract data from relational databases and data warehouses, XML files, flat files and other sources before transforming them and loading them into other applications.
SSIS can be deployed on premises or in the cloud. Azure Integration Services is cloud-only.

Concerning licence costs (from $3,71 per core), it depends on the version, but there is also a free edition (Express and Developer).

Panoply

Panoply is the only cloud ETL provider and data warehouse combination. With 100+ data connectors, ETL and data ingestion is fast and easy, with just a few clicks . Panoply is actually using an ELT approach (rather than traditional ETL), which makes data ingestion much faster and more dynamic, since you don’t have to wait for transformation to complete before loading your data. And since Panoply builds managed cloud data warehouses for every user, you won’t need to set up a separate destination to store all the data you pull in using Panoply’s ELT process.

License costs are around $249/month (includes managed Amazon Redshift cluster).

Stich

Stitch is a self-service ETL data pipeline solution built for developers. The Stitch API can replicate data from any source, and handle bulk and incremental data updates. Its REST API supports JSON or transit, which helps enable automatic detection and normalization of nested document structures into relational schemas. Stitch can connect also to Amazon Redshitf and Google BigQuery Architecture, as well as Postgres architecture – and integrates with BI tools. Stitch is typically designed to collect, transform and load Google analytics data into its own system, to automatically give business insights on raw data. 

Licence costs varies depending on data size from $100 to $1,000/month.