Why Green Screens product is different?

The most frequent question we were asked is "Why we are different than competitors?".

In this article we will outline some unique features our product has that makes it different than our competitors.

Web only

Many competitors say they have web only solution. Some of them are rendering 5250 terminals screens on the server and sending pure HTML to the browser. Some use Java applets which by the way are discontinued product.

But only few competitors use WebSocket. The question is how WebSocket is used?

Our WebSocket implementation is highly secured and size optimized being bandwidth friendly.

We have spool web printing, screen export feature to export screens to Excel or Word with defined templates. Full RTL language support, themes, keyboard mapping, high level of customization and many more.

Find out more in techincal blog or play with Offline Demo


Some competitors will say "we don't need mobile when we are web ready, it works in mobile also". That's a false statement.

Mobile devices switch between mobile signals or between WIFI to WIFI loosing connection and changing IP address. That means terminal connection will break. Signing in over and over again is not quite user friendly.

Our solution can survive connection and IP switch and let you continue where you stopped. Even if that does not work, macro support enables easy "one tap" entry to your system and to specific screen.

What about other mobile apps? Simply said ...they are pure telnet clients that can't survive connection or IP switch.

Additionally - our mobile app supports virtual printer writer, printing to various formats including support for POS printers. We did not find any other web only or mobile terminal product with support for virtual printer.

Besides printing support, we have support for small factor devices with "reduced screen rendering" feature, barcode OCR based on device camera, macros and OTP support.

Find more about mentioned features here


We did not find in any of our competitors that they support remote virtual printer for SCS spools.

We have full support inside our browser and mobile solution including various printing drivers that can print to PDF, TEXT, HTML, JSON or HTML based templates.

File transfer

We support simple IFS file transfers directly from web terminal.


Our Green Screens Terminal Service is written purely in Java. Sever side product can be installed on any hardware platform supporting Java 1.8.

From IBM I, AIX, Linux, MS Windows etc... Couple of notable competitors have only OS dependable installation. Often with very complex installation procedure.

Green Screens Terminal Service can be deployed as a set of Java Web Archive (*.war) files in any modern Java web server.


Our solution is ideal for cloud environment with easy install in Docker environment. With cluster feature one can run as many instances as needed without additional cost.

All instances in the same group will synchronize automatically. Changes made on one instance will reflect in other instances which simplifies maintenance.

With full proxy support it is easy to create redundancy instances and hot-plug.

Find more about Docker support


All our competitors rely only on SSL. Additionally, we implement many other security features. Just to name a few - 2FA (2 factor authentication) which is "a must" by today online security standards, WTMA - signing with mobile without need to enter credentials inside web environment. That feature prevents from password hijack. URL sharing prevention, IP filter, mobile access control which complies with GDPR and many more.

More details can be found here


Average terminal screen is 2KB. Not too much for small businesses, but a lot for big ones. Multiplying this with 5000 workstations we can easily calculate max. throughput of 10MB/s.

Consider outsourcing your system into cloud and paying for high bandwidth only for terminal screens?

Web page generated terminal screens can easily reach 20KB/request which leads to throughput of 100Mb/s for 5000 workstations.

Our system uses only 700 bytes/request in average reducing bandwidth requirements and dramitically improve responses.


Our web API become quite powerful over time and enable us programmatic integration with other web applications. By using our JavaScript based web terminal API only the sky is the limit.

Try some simple examples in Playground Page or explore API documentation.


Only few competitors support screen modernization. Most notable solutions are desktop only, requires local installation. Web based solutions often tides you to the product owner and have complex workflow. Many such solutions requires original code to be modified, refactored or require double maintenance.

Our solution is based on web standards only, open and does not tide you to us. One can hire local company to modernize terminal screens or SCS spools with web templates and web technology they want.

To not to forget, our mobile application fully supports web-based screen modernization. We do not know for any mobile product out there that supports screen modernization for mobile devices.

Find more about modernization at following links:


Do you remember IBM EHLL? A DLL based client for integration of various custom solutions with 5250 terminals.

We have it.

Write your program in any technology you want, use our HLL service and DLL module to link with Green Screens Web 5250 terminal running in your browser.

We already have implementation running with Link IT product from our partner VRTech.

NOTE: Only Chrome and Firefox. In close future support will be added for MS Edge.


There is very light open source version based on opensource tn5250j lib. without our technical support and without many features mentioned here, but still useful to many.

Download, compile and play with source from our GitHub repository.

For more detailed list of features, please see the list on our web site here.