Open Roberta Lab

Developer/Provider:Fraunhofer IAIS
Type of application:Web application
Operating system:Cross platform
Account required:No, optional for more features
Usable offline:Yes, an individual server can be hosted with an image of Open Roberta: Local installation

Open Roberta is an editor developed by the Fraunhofer Institute, which can be used to program various microcontrollers and robots in the graphical programming language NEPO®. The Wiki of Open Roberta contains general information on how to use the editor and an introduction to programming the Calliope mini.

to the editor

File management

Save project

The storage format for the Open Roberta projects is XML.
With an account, projects can be saved online on the server and accessed under "my programs" from different computers.

Transmit to the Calliope mini

The file format to run the program on the Calliope mini is .HEX. The hex file does not contain any information about the program structure in the editor. This means that only XML files can be exported and imported.

Share program

Programs can be shared as a link. However, this is very long, because in it all the information about the program structure has been stored. With an account it is possible to share the programs directly with other users or to upload them to the gallery, to which everyone has access (even without an account). In addition, programs of multiple students without an account can be sent to a group owner with an account in group management.

Program features

Simulation and Debugger

With the simulation and the debugger there is it is possible to test the program without having to transmit it to the Calliope mini and to check for errors.

Group management

With the group management it is possible, for example, as a teacher to view the projects of the students without them having to create their own account. The teacher can also share programs for the group.

Open Roberta Wiki


With an account it is possible to share the projects to the gallery and make them available for other users. However, no user account is required to browse through all the published projects.

Open Roberta Wiki

Robot configuration

The robot configuration provides an overview of all internal sensors/actuators and external ones can be added and configured.

Open Roberta Wiki

Programming concepts

Block-based programmingYes
Text-based programmingNo, but the source code can be displayed in C/C++
Events (event-based programming)No, procedural
Lists / multidimensional listsYes / No
Loops: While / For / ForeachYes / Yes / Yes
Functions / with parameters / with return valueYes / Yes / Yes
Serial communicationYes
Sensors/actuators extensionsYes, preset selection

Documenting and commenting


Comments can be stored directly at the blocks. In addition, there is a separate comment block, so that the comment is also displayed in the generated source code editor.


In order to create teaching material or own instructions for programs, it is helpful to take screenshots. With the NEPO-2-Image web tool, the screenshots can be created both as vector graphics (svg) and as high-resolution pixel graphics (png). The blocks are all displayed individually and as a whole program with a transparent background, so that they can be placed freely on the teaching material.


Documentation and help

If the question mark symbol on the right corner of the editor is clicked, a detailed documentation of the individual programming blocks opens. Alternatively, the direct information about the block can be accessed by selecting it with a right mouse click and clicking Help .