loa-sim
Combat Power simulator for Lost Ark (NA / CE)
Load your character, change your gear, and see exactly what each change does to your Combat Power.
loa-sim.vercel.app · ramen shop Discord · character data from lostark.bible
What it does
- Starts from your real number. The simulator begins at lostark.bible's exact Combat Power and applies every edit
on top of it.
- Edit everything: honing and advanced honing, bracer, Sidereal weapons, accessories line by line, bracelet,
gems, engravings and ability stones, ark grid cores and astrogems, karma, and skins. CP updates as you type.
- Next Upgrades: the best next steps for your character, ranked by Most CP or Per gold. Honing costs come
from material prices you enter, with your bound mats used first, and show average and pity cost.
- Whole accessories: accessories are compared as whole pieces, the way you'd buy them on the market. Pick which
rolls to consider (H-H, H-M, M-H, H-L, L-H, M-M).
- Standing: see where your CP ranks, now and after your changes.
- Works on your phone.
- Keep your upgrade plans. Save named simulations in your browser, select a saved plan from the purple picker when you want to restore it, or export/import a JSON file to back up or share your starting gear and edits. Current edits autosave in your browser and restore when you reopen the same character snapshot.
- Compare honing books. Hellfire books appear with the lower T4 materials: enter bound stock and market prices. Their verified success bonuses and eligible levels apply automatically; the breakdown compares books and breath, average savings, first-tap odds and market break-even. Serca books await verified rules.
How to use
- Open loa-sim.vercel.app.
- Pick your region and type your character name (or paste a lostark.bible link), or sign in with lostark.bible to
load your roster.
- Change things and watch the CP. Use Next Upgrades to see what to do next.
To get your current gear, set it up in game, go to character select, then hit reload on the character. That's when a
fresh snapshot reaches lostark.bible.
FAQ
Is my data stored anywhere?
No. Loaded characters, your roster and your edits stay in your browser. The app only reads what lostark.bible already
shows publicly.
Why is my number slightly off after an edit?
Some parts of the CP formula aren't public. Rows marked ≈ are estimates. Bracer numbers are a KR preview.
Why no gold cost for cores and astrogems?
Their gold efficiency can't be reliably calculated, so they're ranked by CP only.
Feedback or a bug?
Join the ramen shop Discord.
Disclaimer
loa-sim is a fan-made tool. It is not affiliated with or endorsed by Smilegate RPG or Amazon Games. Lost Ark game data
and icons © Smilegate RPG. Character data comes from lostark.bible.
Made with ♥ by Soulshan@Inanna.
Development
npm install
npm run dev
Then open http://localhost:5173.
npm test
Layout
src/lib/upgrade-planner/ holds the simulator and Next Upgrades, built to drop into lostark.bible. See
INTEGRATION.md.
simulate.ts is the simulator engine; Simulator.svelte and sim/ are its UI.cp.ts / tables.ts / honing-data.ts hold the CP formula and battle point tables.live-upgrades.ts, accessory-sets.ts, honing-cost.ts and UpgradePlanner.svelte are Next Upgrades.
src/lib/demo/ and src/routes/ hold the SvelteKit app around it.src/lib/server/bible.ts loads live characters.scripts/bake-game-data.mjs regenerates the honing tables, icons and bracelet catalog from the game data.legacy/ has the first standalone prototype.
Loading a character
Players load their own character on the home page, three ways:
- Sign in with lostark.bible (OAuth, Authorization Code + PKCE). The app reads the player's linked rosters and
lists their characters; picking one loads it. The token stays in the player's browser for its 90 days.
- Load by name: type a name (or bible link) and press Load.
- Paste: open the character's lostark.bible data link, copy all of it and paste it in (the fallback).
Loading goes through this app's server (/api/character/<region>/<name>): browsers can't fetch bible's character
data themselves (no CORS), and bible's OAuth API has no gear yet. lostark.bible's developer has OK'd fetching it
server-side, one character per player action; the server caches each character for a few minutes and shares one
request between simultaneous loads. Set BIBLE_SERVER_FETCH=0 to turn it off (see .env.example); players then
paste instead. Either way the data is decoded and saved in the player's browser, so a return visit opens straight
into the simulator.
Reports
The Updates card's Report it opens a form that posts to /api/report; the server files it as a GitHub issue
with GITHUB_ISSUES_TOKEN (fine-grained, this repo only, Issues: read and write), labelled bug / enhancement
plus from-site, so players don't need a GitHub account. A hidden spam-trap field and a per-address limit (3 per
10 minutes) keep bots out. Without the token the form says reporting is off and links to GitHub instead.
The selected region is remembered in localStorage; an explicit region in a reload link takes precedence.
OAuth redirect URIs registered with lostark.bible: https://loa-sim.vercel.app (production client) and
http://localhost:5173/oauth-test (development client; /oauth-test also hosts a dev-only API inspector).
