Here is a quick list of technical consultant and developer tools (free or open-source), which have proven useful over the years to me. Hopefully, this information will be of use to you as well.
Text and Code Editors
Notepad++, which I have been using for years now, is a free source code editor which supports several programming languages running under the MS Windows environment (governed by GPL License). I have repeatedly found Notepad++ extraordinarily useful. Especially, the language features (e.g. Shell, XML, SQL) or needing to work with files and data without the worry of hidden character.
Image and Screenshot Tools
Greenshot is a light-weight screenshot software tool for Windows, which can be very helpful for capturing application screenshots. Greenshot allows quick creation of screenshots, easy annotation, highlighting and obfuscating using the built-in image editor and sending the screenshot to a file, the clipboard, a printer or as e-mail attachment
PhotoScape is an easy photo editing software editing, fixing and enhance photos, screenshots, and images.
Useful Open Source Tools for Project Plans
Google – gantter for google drive
This tool can be to create projects and Gantter charts when you don’t have a project planning tool available. this tool does seem to have some size and complexity limitations.
This is a useful Microsoft Project plan view for those times when you have MS project available.
I have found this tool to be a useful substitute for MS Project and I have not had any issues with size or complexity limitations. I have also found the export and import capability useful when working on projects teams who do no use a consistent project planning tool. Additionally, if you are or have been an MS Project user, you should most of the functionality moderately intuitive, at least, I didn’t have any problems adapting.
Microsoft Visio 2016 Viewer
The Microsoft Visio Viewer can be very handy when you need to view Visio diagrams and there are not enough licenses to go around, or you just need to read them and have no need to create or update the diagrams.
Google chrome add-in
if you are a chrome user you may want to consider this alternative. Especially, if you are a MAC and/or Linux user.