MassProBono was developed by the Volunteer Lawyers Project in the early 2010s through a Legal Services Corporation Technology Initiative Grant, contracting with Pro Bono Net, a nonprofit that hosts legal aid and pro bono websites throughout the U.S. and Canada, and the Massachusetts Legal Aid Websites Project at the Massachusetts Law Reform Institute.

To create the Pro Bono Opportunities Guide, MassProBono partnered with the Massachusetts Bar Association, which had built an extensive statewide listing of pro bono opportunities. The Pro Bono Opportunities Guide on this website builds on the MBA's pro bono catalog and incorporates the interactive functions of the Pro Bono Net platform to create a robust new tool to facilitate pro bono matching. MassProBono now lists over 70 organizations offering Pro Bono opportunities and has over 2000 members.

MassProBono has undergone many changes over the years to best fit the changing needs of those who use it, including building out mobile app capacity and generating a series of guides and checklists for common pro bono areas of law. In 2020, in partnership with the Access to Justice Commission’s COVID-19 Task Force, MassProBono launched the Massachusetts COVID-19 Pro Bono Portal which supported organizations in listing projects related to the pandemic, designing remote pro bono opportunities, and recruiting volunteers during this time of urgent and great need. As a result of this work, several remote clinics and programs remain as ways to get involved with pro bono work across the state.

The creation of MassProBono came out of decades of work to envision technology which could comprehensively support access to justice for low-income and vulnerable populations. As of June 2023, MassProBono is operated by the Legal Aid Websites Project at Massachusetts Law Reform Institute, which houses a comprehensive suite of websites geared toward making legal information accessible to different audiences, including MassLegalServices.org to support legal aid advocates and MassLegalHelp to provide understandable legal information to the public. These statewide websites offer a network of resources for legal aid and nonprofit advocates, the private bar, law students and others engaged in pro bono, self-represented litigants, and members of the public seeking legal information.