Here are some academic conferences or workshops in July that are virtual and free for non-authors. Most, if not all, of them still require registration.

IEEE:
• IEEE International Conference on Application-specific Systems, Architectures and Processors (Jul. 6 – Jul. 8): https://asap2020.cs.manchester.ac.uk/index.html
• IEEE International Conference on Multimedia and Expo (Jul. 6 – Jul. 10): https://www.2020.ieeeicme.org/
• IEEE Summer Topicals Meeting Series (Jul. 13 – Jul. 15): https://www.ieee-sum.org/
• International Workshop on Integrated Microwave and Millimetre-wave Circuits (Jul. 16 – Jul. 17): https://inmmic.org/
• Virtual Workshop on Thermal Management for Power Electronics and Storage (Jul. 28 – Jul. 30): https://semi-therm.org/
• International Multidisciplinary Engineering Research Conference (Jul. 28 – Jul. 30): https://mercon.uom.lk/index.html#intro

ACM:
• Eurographics Symposium on Geometry Processing (Jul. 6 – Jul. 8): https://sgp2020.sites.uu.nl/
• Annual ACM/IEEE Symposium on Logic in Computer Science (Jul. 8 – Jul. 11): https://lics2020.saarland-informatics-campus.de/
• High-Performance Graphics (Jul. 13 – Jul. 16): https://www.highperformancegraphics.org/2020/
• ACM International Conference on Distributed and Event-based Systems (Jul. 13 – Jul. 17): https://2020.debs.org/
• ACM SIGSOFT International Symposium on Software Testing and Analysis (Jul. 18 – Jul. 22): https://conf.researchr.org/home/issta-2020
• Conversational User Interfaces (Jul. 22 – Jul. 24): https://cui2020.com/
• International Conference on Social Media & Society (Jul. 22 – Jul. 24): https://socialmediaandsociety.org/
• Computational Complexity Conference (Jul. 28 – Jul. 30): https://computationalcomplexity.org/Archive/2020/fullsite/index.php

SIAM:
• SIAM/CAIMS Annual Meeting (Jul. 6 – Jul. 17): https://www.siam.org/conferences/cm/conference/an20
• SIAM Conference on Imaging Science (Jul. 6 – Jul. 17): https://www.siam.org/conferences/cm/conference/is20
• SIAM Workshop on Network Science (Jul. 9 – Jul. 10): https://www.siam.org/conferences/cm/conference/ns20