$ aggregate League of Legends champion mastery across all your accounts
LOLSUMMD solves a specific problem for multi-account League of Legends players: champion mastery history is siloed per account, so your real total for a champion you've played across multiple accounts is invisible to the client. The app lets you add up to 10 accounts by Name#Tag, fetches mastery data for each via the Riot API, and sums points and levels per champion ID to produce a unified view.
Champions can be sorted by name, total mastery points, or combined level. The top three champions are displayed in a podium widget, and the full dataset can be exported as JSON.
Account lookup uses a two-stage Riot API flow. The Name#Tag pair is resolved to a PUUID via the Account API on the appropriate continental platform, then the PUUID is used to fetch per-champion mastery records from the regional endpoint. Riot exposes 14 regional APIs across 4 continental platforms (Americas, Europe, Asia, SEA), and the app maps each region to its correct pair of endpoints.
Mastery aggregation is a straightforward reduce: iterate each account's mastery list, accumulate
{champion_id: {points: N, level: N}} into a shared dictionary, and sort the result. The
frontend parses clipboard paste input splitting on the # separator and submits the
account list as a form POST.
API responses are cached in Redis with a 24-hour TTL. Two cache key namespaces are used:
cache:accounts:{puuid} stores mastery data for a given account, and
cache:name_index:{username}#{tag}#{region} stores the resolved PUUID so repeated
lookups for the same summoner skip the account resolution call. Cache entries are auto-indexed on
write so name-based lookups can hit the cache without re-resolving.
Building around a rate-limited, multi-tier external API forced careful design of the caching layer and request routing from the start. Some key takeaways:
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