Stellaris Tech Tree Viewer (2024)

This provides a set of files to view the technology tree for the 4x strategy game Stellaris.

You can view the latest live snaphsot at

Predominantly this repository contains a python3 tool to generate a HTML/CSS rendering of the tech tree information from the game files.

  • /script/ contains the python code to parse the game files
  • /public/ contains the output from the python tool and some HTML/CSS/JS and other assets to provide a view you can load in a web browser

As best as possible, the display matches columns to tech tiers. Tier 0 (starter techs) will only appear in the leftmost column. The Treant.js toolused within the viewer is not as good at keeping techs from drifting into higher tier columns, i.e. the fourth column is where tier 4 techs should be displayed,Occasionally a tier2 or tier 3 tech with prerequisites may be pushed into the fourth column.

The purple background behind a tech name indicates it is a rare tech. The red background indicates it is a deadly tech.

Clicking on a tech will collapse all its children and color the tile grey.

Hover over the two icons on the right of each tech tile to see more information:

Icon Details
upper … ellipsis icon The tech description, including its rare/dangerous indication and any required DLC. It will also list out the tech prerequistes as a tech may have multiple prerequisistes but only one is indicated in the graph lines. If a tech requires more than one non-starting tier tech, the “…” button will be colored orange.
It will also display any game items that are activated by the tech, i.e. access to ships, weapons, edicts, …
lower ⚄ box icon The weight modifiers. This can often be a complex set of rules. When the weight goes to 0 the card will never be chosen.

Techs requiring a specific DLC are highlighted in yellow. There really arean’t a lot. There is currently no way to change the display based on owned DLCs.

  1. Install python 3.5 or later and prerequisite libraries.
  2. Copy to Edit accordingly. For windows, I use the values below with triple quotes.
     game_dir = r"""C:\Games\Steam\steamapps\common\Stellaris""" workshop_dir = r"""C:\Games\Steam\steamapps\workshop\content\281990"""
  3. Run the python image extraction script.
     python script\ vanilla
  4. Run the python parser script. It will may print warnings about some items which aren’t handled properly. It will generate public/vanilla/techs.json.
     python script\ vanilla
  5. After parsing, you need to serve the /public/ directory from a web server. Unfortunately it won’t work ifyou try to open the files directly from your local disk. You can easily run a webserver by switching into the public directory and runningpython -m http.server 8000 and connect to http://localhost:8000 in your browser.

This was pulled from a gitlab repo started by bipedalshark, but has not been updated since 2017, v2.0.1. See

Latest images have been merged from (see Alternatives below).

There is another fork of bipedalshark’s code on github managed by tunrar and other contributors. This is active as of July 2020, buthas changed the parser from python to java and split the game file parserand viewer into two separate repositories.

The Stellaris game rules are captured in text data files. Looking in /steamapps/common/Stellaris/common there are folders for many of the games basic concepts.

achievements country_types leader_classes sector_focuses
achievements.txt decisions mandates sector_types
agendas defines map_modes ship_behaviors
ai_budget deposit_categories megastructures ship_sizes
alerts.txt deposits message_types.txt solar_system_initializers
ambient_objects diplo_phrases name_lists special_projects
anomalies diplomacy_economy notification_modifiers species_archetypes
archaeological_site_types diplomatic_actions observation_station_missions species_classes
armies districts on_actions species_names
artifact_actions dynamic_text opinion_modifiers species_rights
ascension_perks economic_categories personalities star_classes
asteroid_belts economic_plans planet_classes starbase_buildings
attitudes edicts planet_modifiers starbase_levels
bombardment_stances ethics policies starbase_modules
buildings event_chains pop_categories starbase_types
button_effects fallen_empires pop_faction_types start_screen_messages
bypass federation_law_categories pop_jobs static_modifiers
casus_belli federation_laws precursor_civilizations strategic_resources
colony_automation federation_perks random_names subjects
colony_automation_exceptions federation_types relics system_types
colony_types galactic_focuses resolution_categories technology
colors game_rules resolutions terraform
component_sets global_ship_designs scripted_effects trade_conversions
component_slot_templates governments scripted_loc tradition_categories
component_tags graphical_culture scripted_triggers traditions
component_templates HOW_TO_MAKE_NEW_SHIPS.txt scripted_variables traits
country_customization lawsuits section_templates war_goals

If you look inside /technology/ you can see files for the main tech areas (physics, social, engineering) and the DLC.

00_apocalypse_tech.txt 00_fallen_empire_tech.txt 00_phys_tech.txt 00_soc_tech_repeatable.txt tier/
00_distant_stars_tech.txt 00_horizonsignal_tech.txt 00_phys_tech_repeatable.txt 00_soc_weapon_tech.txt
00_eng_tech.txt 00_leviathans_tech.txt 00_phys_weapon_tech.txt 00_strategic_resources_tech.txt
00_eng_tech_repeatable.txt 00_megacorp_tech.txt 00_repeatable.txt 00_synthetic_dawn_tech.txt
00_eng_weapon_tech.txt 00_megastructures.txt 00_soc_tech.txt category/

The entries are mostly human readable.

tech_corvette_build_speed = { cost = @tier1cost2 area = engineering tier = 1 category = { voidcraft } prerequisites = { "tech_corvettes" } weight = @tier1weight2 modifier = { shipsize_corvette_build_speed_mult = 0.25 ship_corvette_cost_mult = -0.05 } weight_modifier = { modifier = { factor = 1.25 research_leader = { area = engineering has_trait = "leader_trait_expertise_voidcraft" } } } ai_weight = { modifier = { factor = 1.25 research_leader = { area = engineering has_trait = "leader_trait_expertise_voidcraft" } } }}

Mostly we want to pull out the name, tier, area, category, prerequisites, cost, weight, any adjustments to the weight, and the dlc requirements.

All the short string get maped to more readable English (or whatever language) from the Stellaris/common/localization/english

tech_corvette_build_speed:0 "Standardized Corvette Patterns"tech_corvette_build_speed_desc:0 "Establishing new standards for the modeling and construction of corvettes greatly improves the efficiency of the production pipeline."leader_trait_expertise_voidcraft:0 "Expertise: Voidcraft"

Items that show up with a @, $, or Brittish pound sign are replaceable parameters within a field and get hit with another level of substitution.

The program uses two parsers to read the Stellaris game data files.

  • ruamel.yaml - is used to read the English localization files and dump some weight information
  • a custom yacc based parser is used to read the game rule files

The tech tree viewer uses a Treant.js for displaying the tree. It appears to have been designed for displaying corporate org charts.

The techs.json file is loaded by tech-tree.js and rebuilt into the json expected by Treant.

The custom files for the Stellaris tech viewer are mostly:

  • /public/vanilla/index.html
  • /public/js/tech-tree.js
  • /public/css/tech-tree.cs

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Stellaris Tech Tree Viewer (2024)


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