Lingo4G has very few requirements and can be installed locally or inside a virtualized environment.

Local installation

To install Lingo4G on a local machine, perform the following steps.

  1. Extract Lingo4G ZIP archive to a local directory. We call this directory Lingo4G home directory or L4​G_​H​O​M​E.

  2. Copy your license file ( or license.xml) to the L4​G_​H​O​M​E/conf directory.

    See the License file section for other possible locations of the license file.

  3. (optional) Add L4​G_​H​O​M​E to your command interpreter's search path, so that you can easily run Lingo4G commands in any directory.

  4. (optional) Index example data.

    Most examples in this documentation are based on the arXiv database of scientific paper abstracts. To index arXiv data, perform the indexing and embedding learning steps of the Quick start guide.

  5. (optional) Validate the installation.

    Perform the Starting Lingo4G server and Running Lingo4G Explorer steps of the Quick start tutorial to validate that Lingo4G works correctly on your machine.


Lingo4G does not ship with a docker file. The installation in Docker should be easy to write. Base your Dockerfile on top of a plain Linux, add the required Java version and place the license file under the conf/ folder, much like in the local installation.

You can index your project inside Docker or run Lingo4G Server on top of an immutable index you prepared in advance on a separate machine (which we recommend). You can also redirect and expose the default Lingo4G Server HTTP port (8080) so that it's available outside the Docker environment.

License file

Lingo4G requires a valid license file to run. To get an evaluation license or recover the license you purchased, contact us at

The license is an XML file containing licensee name, as well as the licensing and software maintenance expiration dates. To validate your license file, upload it at The validator shows when your license expires (you will not be able to use Lingo4G beyond that date) and when software maintenance expires (you will not be able to upgrade to versions released after that date). The validator also lets you download all the products covered by the license file.

We e-mail license files inside ZIP archives to prevent spam filters from blocking XML content. Lingo4G accepts both the unpacked license XML file (license.xml) and a ZIP ( archive containing the license XML file.

Lingo4G expects the license XML or ZIP file in one of the following locations:

  • In the L4​G_​H​O​M​E/conf directory.

  • In the conf subdirectory of the project you submit for Lingo4G to work on. In this case, Lingo4G uses the license file to operate only on that project.

Tip: descriptive license file names

Lingo4G loads any file matching the license*.xml or license*.zip pattern. Therefore, you can give your license keys more descriptive names, such as license-production.xml or

Distribution files

Lingo4G distribution consists of the following folders and files:

Configuration files, license file.
Project files for the example data sets.
Lingo4G implementation and dependencies.
The default lexical resources like stop words and label dictionaries. Example API v2 requests.
Example code: calling Lingo4G REST API from Java.
Java source code for the default document sources and utilities.
Static web applications served by Lingo4G REST API (including Lingo4G Explorer).
Lingo4G documentation, also available on-line.
l4g, l4g.cmd
The Lingo4G command scripts for Linux/Mac and Windows.
Basic information about the distribution, software version and pointers to this documentation.