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Welcome to the Monsterizer

The Monsterizer is a full-featured monster builder tool to help you build and balance monsters for 5th edition Dungeons and Dragons. Start from one of over 300 monsters and NPCs in the SRD, or start fresh and build your monster from scratch.

The monsters created here will follow the CR rules (see “Legal Stuff”, below) established in 5e, allowing you to confidently build exciting new monsters in a matter of minutes.

Legal Stuff

All of the monsters and rules content in this tool are taken from the official SRD. I cannot (and will not) include other official monsters because it would violate Wizards of the Coast’s intellectual property rights.

How Calculating CR Works

The rules used to calculate CR are based in large part upon the rules presented in the Dungeon Master’s Guide, but I’ve made necessary modifications to address portions of those rules which don’t handle certain use cases. For a better understanding of how CR is calculated, I encourage you to acquire a copy of the Dungeon Master’s Guide from your Friendly Local Game Store.

Even with automation, CR can still be a bit “fuzzy”. Things like condition resistances/immunities and “crowd control” effects like fear and paralysis often don’t have a numerical impact on CR. Creatures with special abilities may be more or less challenging than the math indicates, so even with the Monsterizer you may not be able to perfectly estimate your monster’s CR. Consider the calculated CR to be the minimum CR for most creatures, and expect the creature to be more difficult than expected if you add abilities more complex than simple attack/damage actions.

Change Log

  • 1.0.18 – August 8th, 2022 – Bug fixes, allow changing Legendary Actions count
  • 1.0.17 – July 27th, 2022 – Separate inputs for bonus actions and bug fixes
  • 1.0.16 – June 10th, 2022 – Bug fixes
  • 1.0.15 – February 1st, 2022 – Bug fixes
  • 1.0.14 – December 31st, 2021 – Import monsters from previously-exported data
  • 1.0.13 – November 6th, 2021 – Export to Markdown, including special markdown for’s Homebrewery
  • 1.0.12 – November 5th, 2021 – Switch between classic/updated stat block format
  • 1.0.11 – October 22nd, 2021 – Support Markdown in multi-line text fields
  • 1.0.10 – October 14th, 2021 – Made everything prettier
  • 1.0.9 – October 13th, 2021 – Bug fixes
  • 1.0.8 – October 12th, 2021 – Bug fixes
  • 1.0.7 – October 9th, 2021 – Added new “Tactics and CR Calculatiom” section to Actions page to describe the actions used to calculate the creature’s offensive CR. Also add a new “Tactics” field so that you can describe your creature’s preferred combat tactics in the stat block.
  • 1.0.6 – October 7th, 2021 – Improved CR feedback information for Defenses (Actions soon!)
  • 1.0.5 – October 4th, 2021 – Bug fixes
  • 1.0.4 – October 3rd, 2021 – Bug fixes
  • 1.0.3 – October 3rd, 2021 – Better layout for mobile devices
  • 1.0.2 – October 3rd, 2021 – New “Save as PNG” button and stat block style controls. Cosmetic improvements and bug fixes.
  • 1.0.1 – October 2nd, 2021 – Fixed a bunch of bugs
  • 1.0.0 – October 1st, 2021 – Initial launch

Future Updates

The Monsterizer has room to improve. I have plans to add additional features in the future, but I need to know what people care about most so that I know what to focus on. If you want to see any of the features below, or if you have other ideas for improvements, please email me at .

  • Adaptive color scheme (dark/light mode)
  • Add class levels to monsters
  • Add templates (shadow dragon, etc.) to monsters
  • Auto-calculate CR from spellcasting
  • Better Action inputs. Help formatting atttack entries, auto-calc highest attack/DC.
  • Better CR feedback as you work on the monster
  • Better mobile support. It’s very rough, currently.
  • Export to DnDBeyond (I’m not exactly sure how that will work yet)
  • Export to DMBinder
  • Export to Virtual Tabletops (Currently requested: Fantasy Grounds, Foundry, Roll20)
  • Export to “Gamemaster 5e” app
  • Export to Homebrewery
  • Import data (effectively allowing you to save and share monsterizer data)
  • Improvements to reflect new stat block format used in the Wild Beyond the Witchlight and future supplements.
  • Random monsters
  • Support for CR 31+
  • Style selector for stat block so that you can make it look fancy for screenshots
  • Support “markdown” syntax in description field so that you can write fancy descriptions with nice formatting
  • Tactics advice generated from offensive CR calculations to (mostly) guarantee that your monster is as scary as intended

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