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Language Identifier

The language identifier takes raw text and tries to figure out what language it was written in. The output can either be a plain-text i18n language code or a basic KAF document containing the language and raw input text. The output of the language identifier can then be used to drive further text analysis of for example sentiments and or entities.

Confused by some terminology?

This software is part of a larger collection of natural language processing tools known as “the OpeNER project”. You can find more information about the project at the OpeNER portal. There you can also find references to terms like KAF (an XML standard to represent linguistic annotations in texts), component, cores, scenario’s and pipelines.

Quick Use Example

Install the Gem:

gem install opener-language-identifier

Make sure you run jruby since the language-identifier uses Java.

Command line interface

You should now be able to call the language indentifier as a regular shell command: by its name. Once installed the gem normally sits in your path so you can call it directly from anywhere.

This aplication reads a text from standard input in order to identify the language.

echo "This is an English text." | language-identifier

This will output:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<KAF xml:lang="en" version="2.1">
    <raw>This is an English text.</raw>

If you just want the language code returned add the --no-kaf option like this

echo "This is an English text." | language-identifier --no-kaf

For more information about the available CLI options run the following:

language-identifier --help


You can launch a language identification webservice by executing:

$ language-identifier-server

This will launch a mini webserver with the webservice. It defaults to port 9292, so you can access it at http://localhost:9292/.

To launch it on a different port provide the -p [port-number] option like this:

language-identifier-server -p 1234

It then launches at http://localhost:1234/

Documentation on the Webservice is provided by surfing to the urls provided above. For more information on how to launch a webservice run the command with the -h option.


Last but not least the language identifier comes shipped with a daemon that can read jobs (and write) jobs to and from Amazon SQS queues. For more information type:

$ language-identifier-daemon -h

Description of dependencies

This component runs best if you run it in an environment suited for OpeNER components. You can find an installation guide and helper tools in the OpeNER installer and an installation guide on the OpenerWebsite.

At least you need the following system setup:

Dependencies for normal use:

  • JRuby 1.7 or newer
  • Java 1.7 or newer (there are problems with encodings in older versions).

Dependencies if you want to modify the component:

  • Maven (for building the Gem)

Language Extension

The internal library that actually performs the language identification already supports a lot of languages. For more information about how to extends it for more languages or functionalities, please, visit the website of the tool at

The Core

The component is a fat wrapper around the actual language technology core. Written in Java. Checkout the core/src directory of the package to get to the actual working component.

Where to go from here

Report problem/Get help

If you encounter problems, please email or leave an issue in the issue tracker.


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request


Command Line Interface

Usage: language-identifier [options]
  -v, --version                    Shows the current version
  -k, --[no-]kaf                   Output the language as KAF
  -p, --probs                      Provide probabilities, assumes --no-kaf


Basic Usage
cat example_text.txt | language-identifier    # Basic detection
KAF is the default output
echo "This is english text." | language-identifier    # Defaults to KAF output
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<KAF xml:lang="en" version="2.1">  
    <raw>This is english text.</raw>
Output Probabilities
echo "This is een mix van Nederlandse and English text" | language-identifier --probs    # output probabilities            [nl:0.8579977424996601, en:0.14200189400782184]


You can launch a webservice by executing:


After launching the server, you can reach the webservice at http://localhost:9292.

The webservice takes several options that get passed along to Puma, the webserver used by the component. The options are:

-b, --bind URI                   URI to bind to (tcp://, unix://, ssl://)
-C, --config PATH                Load PATH as a config file
    --control URL                The bind url to use for the control server
                                     Use 'auto' to use temp unix server
    --control-token TOKEN        The token to use as authentication for the control server
-d, --daemon                     Daemonize the server into the background
    --debug                      Log lowlevel debugging information
    --dir DIR                    Change to DIR before starting
-e, --environment ENVIRONMENT    The environment to run the Rack app on (default development)
-I, --include PATH               Specify $LOAD_PATH directories
-p, --port PORT                  Define the TCP port to bind to
                                 Use -b for more advanced options
    --pidfile PATH               Use PATH as a pidfile
    --preload                    Preload the app. Cluster mode only
    --prune-bundler              Prune out the bundler env if possible
-q, --quiet                      Quiet down the output
-R, --restart-cmd CMD            The puma command to run during a hot restart
                                 Default: inferred
-S, --state PATH                 Where to store the state details
-t, --threads INT                min:max threads to use (default 0:16)
    --tcp-mode                   Run the app in raw TCP mode instead of HTTP mode
-V, --version                    Print the version information
-w, --workers COUNT              Activate cluster mode: How many worker processes to create
    --tag NAME                   Additional text to display in process listing
-h, --help                       Show help


The daemon has the default OpeNER daemon options. Being:

Usage: language-identifier <start|stop|restart> [options]
When calling language-identifier without <start|stop|restart> the daemon will start as a foreground process

Environment Variables

These daemons make use of Amazon SQS queues and other Amazon services. The access to these services and other environment variables can be configured using a .opener-daemons-env file in the home directory of the current user.

It is also possible to provide the environment variables directly to the deamon.

For example:

AWS_REGION='eu-west-1' language-identifier start [other options]

We advise to have the following environment variables available:


Daemon Options

-i, --input QUEUE_NAME           Input queue name
-o, --output QUEUE_NAME          Output queue name
    --batch-size COUNT           Request x messages at once where x is between 1 and 10
    --buffer-size COUNT          Size of input and output buffer. Defaults to 4 * batch-size
    --sleep-interval SECONDS     The interval to sleep when the queue is empty (seconds)
-r, --readers COUNT              number of reader threads
-w, --workers COUNT              number of worker thread
-p, --writers COUNT              number of writer / pusher threads
-l, --logfile, --log FILENAME    Filename and path of logfile. Defaults to STDOUT
-P, --pidfile, --pid FILENAME    Filename and path of pidfile. Defaults to /var/run/
    --pidpath DIRNAME            Directory where to put the PID file. Is Overwritten by --pid if that option is present
    --debug                      Turn on debug log level
    --relentless                 Be relentless, fail fast, fail hard, do not continue processing when encountering component errors


Code Language
ar Arabic
bg Bulgarian
bn Bengali
cs Czech
da Danish
de German
el Greek
en English
es Spanish
et Estonian
fa Persian
fi Finnish
fr French
gu Gujarati
he Hebrew
hi Hindi
hr Croatian
hu Hungarian
id Indonesian
it Italian
ja Japanese
kn Kannada
ko Korean
lt Lithuanian
lv Latvian
mk Macedonian
ml Malayalam
mr Marathi
ne Nepali
nl Dutch
no Norwegian
pa Punjabi
pl Polish
pt Portuguese
ro Romanian
ru Russian
sk Slovak
sl Slovene
so Somali
sq Albanian
sv Swedish
sw Swahili
ta Tamil
te Telugu
th Thai
tl Tagalog
tr Turkish
uk Ukrainian
ur Urdu
vi Vietnamese
zh-cn Simplified Chinese
zh-tw Traditional Chinese
This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 261712.