Swift Selection Search - Swiftly access your search engines in a popup panel when you select text in a webpage.

MAXQDA - a professional software for qualitative and mixed methods data analysis

Trufflepiggy - Quick Search - The all-in-one search addon: just select and search. Find on multiple websites at once. Search via overlay, context menu or omnibar. Featuring anonymous profiles. Easy setup: select from 1000+ user generated searches. Cross-browser sync.

ATLAS.ti - ATLAS.ti is a powerful workbench for the qualitative analysis of large bodies of textual, graphical, audio and video data. It offers a variety of sophisticated tools for accomplishing the tasks associated with any systematic approach to "soft" data.

Selection Search - With this extension you can easily search for text you have selected.

QualCoder - A very complete Free and Open Source Software (FOSS) Computer-Assisted Qualitative Data Analysis Software (CAQDAS) written in Python. It works with text, images, and multimedia such as audios and videos.