diff --git a/core/current-page.ts b/core/current-page.ts
index 0b85a840..695df2db 100644
--- a/core/current-page.ts
+++ b/core/current-page.ts
@@ -4,6 +4,10 @@ import { getEnvironment } from './environment.ts'
 import { type Page, pages } from './pages/index.ts'
 import { type Route, router } from './router.ts'
 
+/**
+ * Iterates over all parameters of a page, calling the iterator function
+ * for each parameter store and its corresponding value from the route
+ */
 function eachParam<SomeRoute extends Route>(
   page: Page<SomeRoute['route']>,
   route: SomeRoute,
@@ -22,6 +26,9 @@ function eachParam<SomeRoute extends Route>(
   }
 }
 
+/**
+ * Extracts current parameter values from all parameter stores of a page
+ */
 function getPageParams<SomeRoute extends Route>(
   page: Page<SomeRoute['route']>
 ): SomeRoute['params'] {
diff --git a/core/download.ts b/core/download.ts
index 01d0a215..40c26bee 100644
--- a/core/download.ts
+++ b/core/download.ts
@@ -20,6 +20,10 @@ export interface DownloadTask {
   text(...args: Parameters<typeof request>): Promise<TextResponse>
 }
 
+/**
+ * Detects content type by analyzing the text content for common patterns
+ * like HTML doctype, XML declarations, RSS/Atom feed elements, and JSON Feed format
+ */
 function detectType(text: string): string | undefined {
   let lower = text.toLowerCase()
   let beginning = lower.slice(0, 100)
diff --git a/core/environment.ts b/core/environment.ts
index f0a322bb..9d268c6b 100644
--- a/core/environment.ts
+++ b/core/environment.ts
@@ -131,6 +131,9 @@ export function setIsMobile(isSmallScreen: boolean): void {
 
 const testRouter = atom<BaseRoute | undefined>()
 
+/**
+ * Ensures a route has a hash property, adding an empty string if missing
+ */
 export function addHashToBaseRoute(
   route: BaseRoute | Omit<BaseRoute, 'hash'> | undefined
 ): BaseRoute | undefined {
@@ -144,6 +147,9 @@ export function setBaseTestRoute(
   testRouter.set(addHashToBaseRoute(route))
 }
 
+/**
+ * Converts popup routes to a hash string format (popup=param,popup2=param2)
+ */
 export function stringifyPopups(popups: PopupRoute[]): string {
   return popups
     .map(({ param, popup }) => `${popup}=${param}`)
diff --git a/core/feed.ts b/core/feed.ts
index f6624fbe..c7ba9237 100644
--- a/core/feed.ts
+++ b/core/feed.ts
@@ -66,6 +66,7 @@ export async function changeFeed(
   await recalcPostsReading(feedId)
 }
 
+/** Subscribes to a feed which is currently being previewed */
 export async function addCandidate(
   candidate: FeedLoader,
   fields: Partial<FeedValue> = {},
diff --git a/core/filter.ts b/core/filter.ts
index ff311206..82fa8e4a 100644
--- a/core/filter.ts
+++ b/core/filter.ts
@@ -119,6 +119,10 @@ export function sortFilters(filters: FilterValue[]): FilterValue[] {
   })
 }
 
+/**
+ * Moves a filter up or down in priority by recalculating its priority value
+ * relative to neighboring filters to maintain sort order
+ */
 async function move(filterId: string, diff: -1 | 1): Promise<void> {
   let store = Filter(filterId, getClient())
   let filter = await loadValue(store)
diff --git a/core/loader/index.ts b/core/loader/index.ts
index 92a5097b..0f2ba01c 100644
--- a/core/loader/index.ts
+++ b/core/loader/index.ts
@@ -5,10 +5,30 @@ import { jsonFeed } from './json-feed.ts'
 import { rss } from './rss.ts'
 
 export type Loader = {
+  /**
+   * Returns all urls found in the html document itself and in its http headers.
+   * Response here is the website response with a html document.
+   */
   getMineLinksFromText(response: TextResponse): string[]
+  /**
+   * Extracts the feed's posts, given feed download task or the response with
+   * the feed's xml.
+   */
   getPosts(task: DownloadTask, url: string, text?: TextResponse): PostsList
+  /**
+   * Given the website html response, returns the default feed url,
+   * e.g. https://example.com/rss for rss feed.
+   */
   getSuggestedLinksFromText(response: TextResponse): string[]
+  /**
+   * Returns feed title, if any
+   */
   isMineText(response: TextResponse): false | string
+  /**
+   * For instance, YouTube loader will return true for youtube.com links or Telegram loader for t.me links.
+   * It detects that URL is 100% for this loader.
+   * It is not used right now because there is no way to detect RSS/Atom link just by URL.
+   */
   isMineUrl(url: URL): false | string | undefined
 }
 
@@ -29,6 +49,9 @@ export interface FeedLoader {
   url: string
 }
 
+/**
+ * Decides which loader to use for the given feed response.
+ */
 export function getLoaderForText(response: TextResponse): false | FeedLoader {
   let names = Object.keys(loaders) as LoaderName[]
   let parsed = new URL(response.url)
diff --git a/core/loader/utils.ts b/core/loader/utils.ts
index 368fca71..168ba986 100644
--- a/core/loader/utils.ts
+++ b/core/loader/utils.ts
@@ -4,10 +4,15 @@ export function isString(attr: null | string): attr is string {
   return typeof attr === 'string' && attr.length > 0
 }
 
+/** Detects that the server responded with a html document */
 export function isHTML(text: TextResponse): boolean {
   return text.text.toLocaleLowerCase().includes('<html')
 }
 
+/**
+ * Given anchor or link element, returns their full url, which includes not only
+ * the explicitly provided base url, but also the base url specified in the document.
+ */
 function buildFullURL(
   link: HTMLAnchorElement | HTMLLinkElement,
   baseUrl: string
@@ -30,6 +35,9 @@ function buildFullURL(
   )
 }
 
+/**
+ * Returns full urls found in the document's <link> elements
+ */
 export function findDocumentLinks(text: TextResponse, type: string): string[] {
   let document = text.parseXml()
   if (!document) return []
@@ -42,6 +50,9 @@ export function findDocumentLinks(text: TextResponse, type: string): string[] {
     .map(link => buildFullURL(link, text.url))
 }
 
+/**
+ * Returns full urls found in the document's <a> elements
+ */
 export function findAnchorHrefs(
   text: TextResponse,
   hrefPattern: RegExp,
@@ -89,6 +100,7 @@ export function findHeaderLinks(
   }, [])
 }
 
+/** Returns the unix timestamp of a date */
 export function toTime(date: null | string | undefined): number | undefined {
   if (!date) return undefined
   let time = new Date(date).getTime() / 1000
@@ -109,6 +121,7 @@ export function findImageByAttr(
   }, [])
 }
 
+/** Returns the unique elements without nulls from array */
 export function unique<T extends number | string = string>(
   collection: Iterable<null | T | undefined>
 ): T[] {
diff --git a/core/menu.ts b/core/menu.ts
index ffdd54c0..9ae962af 100644
--- a/core/menu.ts
+++ b/core/menu.ts
@@ -37,6 +37,10 @@ export let fastMenu = atom<CategoryValue[]>([])
 export let slowMenu = atom<SlowMenu>([])
 export let menuLoading = atom<boolean>(true)
 
+/**
+ * Rebuilds the menu state by categorizing feeds and posts into fast/slow menus
+ * with unread counts and proper category organization
+ */
 async function rebuild(): Promise<void> {
   let [posts, feeds, categories, fastFilters] = await Promise.all([
     loadValue(getPosts()),
diff --git a/core/opened-popups.ts b/core/opened-popups.ts
index 9273d0cc..4007b5bc 100644
--- a/core/opened-popups.ts
+++ b/core/opened-popups.ts
@@ -5,6 +5,10 @@ import { router } from './router.ts'
 
 let prevPopups: Popup[] = []
 
+/**
+ * Manages popup lifecycle by reusing existing popup instances when possible
+ * and destroying unused ones to prevent memory leaks
+ */
 export const openedPopups: ReadableAtom<Popup[]> = computed(router, route => {
   let lastIndex = 0
   let nextPopups = route.popups.map((popup, index) => {
diff --git a/core/pages/add.ts b/core/pages/add.ts
index f56d6195..e629de86 100644
--- a/core/pages/add.ts
+++ b/core/pages/add.ts
@@ -40,8 +40,13 @@ export type AddLinksValue = Record<
 export const addPage = createPage('add', () => {
   let $url = atom<string | undefined>()
 
+  /**
+   * Map of all urls found in the document with urls as keys and loading state
+   * as values.
+   */
   let $links = map<AddLinksValue>({})
 
+  /** List of pending feed urls extracted from the given url */
   let $candidates = atom<FeedLoader[]>([])
 
   let $error = computed(
@@ -111,6 +116,10 @@ export const addPage = createPage('add', () => {
     $url.set(normalizedUrl)
   })
 
+  /**
+   * Extracts links to all known feed types from the http response containing
+   * the html document
+   */
   function getLinksFromText(response: TextResponse): string[] {
     let names = Object.keys(loaders) as LoaderName[]
     return names.reduce<string[]>((links, name) => {
@@ -118,6 +127,7 @@ export const addPage = createPage('add', () => {
     }, [])
   }
 
+  /** Returns a list of default / fallback links for all feed types */
   function getSuggestedLinksFromText(response: TextResponse): string[] {
     let names = Object.keys(loaders) as LoaderName[]
     return names.reduce<string[]>((links, name) => {
@@ -125,6 +135,9 @@ export const addPage = createPage('add', () => {
     }, [])
   }
 
+  /**
+   * Adds a possible feed url, its meta and type, to the list of possible urls.
+   */
   function addCandidate(url: string, candidate: FeedLoader): void {
     if ($candidates.get().some(i => i.url === url)) return
 
@@ -132,6 +145,11 @@ export const addPage = createPage('add', () => {
     $candidates.set([...$candidates.get(), candidate])
   }
 
+  /**
+   * Given the link to the document, checks every link found in the document
+   * for a feed. Populates the list of pending urls, "candidates".
+   * Also accepts a direct feed link.
+   */
   async function addLink(
     task: DownloadTask,
     url: string,
diff --git a/core/refresh.ts b/core/refresh.ts
index a7b5c883..7b88add1 100644
--- a/core/refresh.ts
+++ b/core/refresh.ts
@@ -41,6 +41,10 @@ export const refreshProgress = computed(refreshStatistics, stats => {
 let task: DownloadTask
 let queue: Queue<{ feed: FeedValue }>
 
+/**
+ * Determines if a post was already added to a feed by comparing timestamps
+ * or origin IDs to prevent duplicate posts during refresh
+ */
 function wasAlreadyAdded(feed: FeedValue, origin: OriginPost): boolean {
   if (origin.publishedAt && feed.lastPublishedAt) {
     return origin.publishedAt <= feed.lastPublishedAt
diff --git a/core/router.ts b/core/router.ts
index 3722e5b2..6d8a7abe 100644
--- a/core/router.ts
+++ b/core/router.ts
@@ -130,6 +130,10 @@ function checkPopupName(
   return !!popup && popup in popupNames
 }
 
+/**
+ * Parses popup routes from hash string format (popup=param,popup2=param2)
+ * into an array of popup route objects
+ */
 export function parsePopups(hash: string): PopupRoute[] {
   let popups: PopupRoute[] = []
   let parts = hash.split(',')