The tech tree is provided as a Google Sheets document, which is available here:
https://docs.google.com/spreadsheets/d/1jycBLdcoLE78IyuLtQ5rms_pH0P3QYeDovoYOV-UEls/edit?usp=sharing

The game tech data is found in ResearchAreas3.dat, a CSV-file in the "data" folder of the installation location.

You cannot pick what techs your scientists research, so the techs are not necessarily discovered in the order provided, a tech may be bypassed temporarily if it's discovery chance is <100%. No tech is locked out permanently.

You can view which techs have been researched by double-clicking on a tech group in game research window.

"Year" refers to the base year of the tech, before that date you have to pay extra beakers to open the technology.

"Spread" means that the technology is high-visibility, so once one nation discovers it, it becomes more likely that other nations will research the tech as well. In essense, if you know it's possible, you're already halfway to inventing it.

"Chance" means likelyhood of this tech project being picked when the previous one in the list was finished or skipped. If the tech is skipped, it becomes available to pick the next time a new technology project is selected. The hardest tech to discover in the game is helicopter SAR at 8% chance.

"Air-to-ground rockets" give fighters ability to carry rockets on medium "bomb" load, this is not indicated in the game.

"Advanced airborne radar", "Night airship operations" and "Night air operations" enable air missions for associated plane types, night operations have to be enabled in advance for each individual air unit, it is too late to start practising night time flying in combat.