need your mainframe to be

Cobos is the most advanced Smart Development Environment (SDE) dedicated to mainframe application development (RPG, COBOL, PL/I).

Based on Eclipse, Cobos combines the best of both worlds by capitalizing on the open source community innovation and on the mainframe best practices.

Discover Cobos Features

Discover Cobos Release Notes

RPG Convertor :
Conversion from RPG IV to Free-Form
2 types of conversion :
- Free and/or Mixed
- Fully-Free

Traffic Player :
Traffic Player is a Telnet flow recorder
- Allowing the development and testing of applications
requiring a screen-type resource without requiring the Mainframe
- Allowing to replay the recorded traceLaunch remote compilation of generated programs


Cobos  is the disruptive IDE for mainframe developers.

Modern Editors

Mainframe Ready


Eclipse-based COBOL IDE

The COBOL file editor of Cobos brings the best of Eclipse to COBOL programers: a quick and simple browsing into files with the Outline, Syntax coloring, Autocompletion, Open declaration, Compilation error notifications, Code templates, Changes tracking, Versioning... . All these features have been tailor-made for the COBOL development. Cobos adds to these very convenient features some outstanding features such as a "Word like" revision mode, unfolding COBOL sources with COPY REPLACING expansion, customizable tabulations, mainframe-like CAPS ON.

Ready for the Mainframe

Cobos comes with features & components enabling a deep and powerful integration with your mainframe environments, such as z/Navigator, je3270 (terminal emulator, a remote FTP access, extended CVS support...).

Fit with all environments

Big Blue is not your compilation target? Cobos is also packaged for Windows and UNIX operating systems, with additional features such as remote compilation and local program build capabilities, FTP access to UNIX resources...

And many other features…

Cobos provides mainframe developers with many cool features, in order to make mainframe application development more agile and to fit with specific environements: various SCM tool support, FTP remote access, local program build, 3270/5250 terminal emulator, COBOL, JCL, REXX, PL1, RPG editors …

Cobos 5.2 is now available !

Cobos the professional mainframe Smart Development Environment for Eclipse has been released. Thanks to Cobos, work locally (edit, compile, etc.) on your workstation (Windows and Linux) or connected to your remote environments mainframe IBM i, IBM z/os, AIX, Unix and Windows.

On the blog

Cobos 5.2 Release Notes

Release 5.2.0 [2021-12-17] RPG Converter Conversion from RPG IV to Free-Form (i.e. RPGLE and/or SQLRPGLE source files) Conversion Options : 2 types of conversion : Free and/or Mixed (if there is [...]

Cobos 5.1 Release Notes

Release 5.1.4 [2021-09-06] This release solves the following bugs: 00380 – Cobos4i: Regarding Cobos4i Edit member (locale file extension) (#0101896) 00448 – Cobos4i: Null pointer [...]