Liferay keeps lot of variables inside template context. Following variables available in Velocity & FreeMarker templates.
First check the variable you are looking for is already presents in template init file
/portal-master/modules/apps/foundation/frontend-theme/frontend-theme-unstyled/src/main/resources/META-INF/resources/_unstyled/templates/init.ftl
<#-- ---------- Common variables ---------- -->
<#assign theme_display = themeDisplay />
<#assign portlet_display = portletDisplay />
<#assign theme_timestamp = themeDisplay.getTheme().getTimestamp() />
<#assign theme_settings = themeDisplay.getThemeSettings() />
<#assign root_css_class = languageUtil.get(locale, "lang.dir") />
<#assign css_class = htmlUtil.escape(bodyCssClass!) />
<#assign css_class = css_class + " " + htmlUtil.escape(theme_display.getColorScheme().getCssClass()) + " yui3-skin-sam" />
<#if layout??>
<#assign page_group = layout.getGroup() />
</#if>
<#if layoutTypePortlet.hasStateMax()>
<#assign css_class = css_class + " page-maximized" />
</#if>
<#assign css_folder = theme_display.getPathThemeCss() />
<#assign images_folder = theme_display.getPathThemeImages() />
<#assign javascript_folder = theme_display.getPathThemeJavaScript() />
<#assign templates_folder = theme_display.getPathThemeTemplates() />
<#assign full_css_path = fullCssPath />
<#assign full_templates_path = fullTemplatesPath />
<#assign css_main_file = htmlUtil.escape(portalUtil.getStaticResourceURL(request, "${css_folder}/main.css")) />
<#assign js_main_file = htmlUtil.escape(portalUtil.getStaticResourceURL(request, "${javascript_folder}/main.js")) />
<#assign company_id = company.getCompanyId() />
<#assign company_name = company.getName() />
<#assign company_logo = htmlUtil.escape(theme_display.getCompanyLogo()) />
<#assign company_logo_height = theme_display.getCompanyLogoHeight() />
<#assign company_logo_width = theme_display.getCompanyLogoWidth() />
<#assign company_url = theme_display.getURLHome() />
<#if !request.isRequestedSessionIdFromCookie()>
<#assign company_url = portalUtil.getURLWithSessionId(company_url, request.getSession().getId()) />
</#if>
<#-- ---------- LPS-66428 ---------- -->
<#assign is_default_user = user.isDefaultUser() />
<#assign is_female = user.isFemale() />
<#assign is_male = user.isMale() />
<#assign is_setup_complete = user.isSetupComplete() />
<#assign language = locale.getLanguage() />
<#assign language_id = user.getLanguageId() />
<#assign time_zone = user.getTimeZoneId() />
<#assign user_birthday = user.getBirthday() />
<#assign user_comments = user.getComments() />
<#assign user_email_address = user.getEmailAddress() />
<#assign user_first_name = user.getFirstName() />
<#assign user_greeting = htmlUtil.escape(user.getGreeting()) />
<#assign user_id = user.getUserId() />
<#assign user_last_login_ip = user.getLastLoginIP() />
<#assign user_last_name = user.getLastName() />
<#assign user_login_ip = user.getLoginIP() />
<#assign user_middle_name = user.getMiddleName() />
<#assign user_name = user.getFullName() />
<#assign w3c_language_id = localeUtil.toW3cLanguageId(theme_display.getLanguageId()) />
<#assign is_login_redirect_required = portalUtil.isLoginRedirectRequired(request) />
<#assign is_signed_in = theme_display.isSignedIn() />
<#assign group_id = theme_display.getScopeGroupId() />
<#-- ---------- URLs ---------- -->
<#assign show_control_panel = theme_display.isShowControlPanelIcon() />
<#if show_control_panel>
<#assign control_panel_text = languageUtil.get(locale, "control-panel") />
<#assign control_panel_url = htmlUtil.escape(theme_display.getURLControlPanel()) />
</#if>
<#assign show_home = theme_display.isShowHomeIcon() />
<#if show_home>
<#assign home_text = languageUtil.get(locale, "home") />
<#assign home_url = htmlUtil.escape(theme_display.getURLHome()) />
<#if !request.isRequestedSessionIdFromCookie()>
<#assign home_url = htmlUtil.escape(portalUtil.getURLWithSessionId(home_url, request.getSession().getId())) />
</#if>
</#if>
<#assign show_my_account = theme_display.isShowMyAccountIcon() />
<#if show_my_account>
<#assign my_account_text = languageUtil.get(locale, "my-account") />
<#if theme_display.getURLMyAccount()??>
<#assign my_account_url = htmlUtil.escape(theme_display.getURLMyAccount().toString()) />
</#if>
</#if>
<#assign show_sign_in = theme_display.isShowSignInIcon() />
<#if show_sign_in>
<#assign sign_in_text = languageUtil.get(locale, "sign-in") />
<#assign sign_in_url = htmlUtil.escape(theme_display.getURLSignIn()) />
</#if>
<#assign show_sign_out = theme_display.isShowSignOutIcon() />
<#if show_sign_out>
<#assign sign_out_text = languageUtil.get(locale, "sign-out") />
<#assign sign_out_url = htmlUtil.escape(theme_display.getURLSignOut()) />
</#if>
<#-- ---------- Page ---------- -->
<#assign the_title = "" />
<#assign selectable = theme_display.isTilesSelectable() />
<#assign is_maximized = layoutTypePortlet.hasStateMax() />
<#assign is_freeform = themeDisplay.isFreeformLayout() />
<#assign page_javascript_1 = "" />
<#assign page_javascript_2 = "" />
<#assign page_javascript_3 = "" />
<#if layout??>
<#assign page = layout />
<#assign is_first_child = page.isFirstChild() />
<#assign is_first_parent = page.isFirstParent() />
<#assign the_title = languageUtil.get(locale, the_title, page.getName(locale)) />
<#assign is_portlet_page = false />
<#if page.getType() = "portlet">
<#assign is_portlet_page = true />
</#if>
<#assign typeSettingsProperties = layout.getTypeSettingsProperties() />
<#if typeSettingsProperties??>
<#assign page_javascript = typeSettingsProperties["javascript"]! />
</#if>
<#assign site_name = htmlUtil.escape(page_group.getDescriptiveName()) />
<#assign community_name = site_name />
<#assign is_guest_group = page_group.isGuest() />
<#if is_guest_group>
<#assign css_class = css_class + " guest-site" />
</#if>
<#if is_signed_in>
<#assign css_class = css_class + " signed-in" />
<#else>
<#assign css_class = css_class + " signed-out" />
</#if>
<#if layout.isPublicLayout()>
<#assign css_class = css_class + " public-page" />
<#else>
<#assign css_class = css_class + " private-page" />
</#if>
<#if page_group.isLayoutPrototype()>
<#assign css_class = css_class + " page-template" />
</#if>
<#if page_group.isLayoutSetPrototype()>
<#assign css_class = css_class + " site-template" />
</#if>
<#if page_group.isCompany()>
<#assign site_type = "company-site" />
<#elseif page_group.isOrganization()>
<#assign site_type = "organization-site" />
<#elseif page_group.isUser()>
<#assign site_type = "user-site" />
<#else>
<#assign site_type = "site" />
</#if>
<#assign css_class = css_class + " " + site_type />
<#assign site_default_public_url = htmlUtil.escape(page_group.getDisplayURL(theme_display, false)) />
<#assign community_default_public_url = site_default_public_url />
<#assign site_default_private_url = htmlUtil.escape(page_group.getDisplayURL(theme_display, true)) />
<#assign community_default_private_url = site_default_private_url />
<#assign site_default_url = site_default_public_url />
<#assign community_default_url = site_default_url />
<#if layout.isPrivateLayout()>
<#assign site_default_url = site_default_private_url />
<#assign community_default_url = site_default_url />
</#if>
</#if>
<#assign the_title = "" />
<#if layout.getHTMLTitle(locale)??>
<#assign the_title = layout.getHTMLTitle(locale) />
</#if>
<#if pageTitle??>
<#assign the_title = pageTitle />
</#if>
<#if pageSubtitle??>
<#assign the_title = pageSubtitle + " - " + the_title />
</#if>
<#if tilesTitle?has_content>
<#assign the_title = languageUtil.get(locale, tilesTitle) />
</#if>
<#if page_group.isLayoutPrototype()>
<#assign the_title = page_group.getDescriptiveName(locale) />
</#if>
<#if !tilesTitle?has_content>
<#assign the_title = htmlUtil.escape(the_title) />
</#if>
<#if the_title ?has_content && company_name != site_name && !page_group.isLayoutPrototype()>
<#assign the_title = the_title + " - " + site_name />
</#if>
<#if layouts??>
<#assign pages = layouts />
</#if>
<#-- ---------- Logo ---------- -->
<#assign logo_css_class = "logo" />
<#assign use_company_logo = !layout.layoutSet.isLogo() />
<#assign site_logo_height = company_logo_height />
<#assign site_logo_width = company_logo_width />
<#if (company.getLogoId() == 0) && use_company_logo>
<#assign logo_css_class = logo_css_class + " default-logo" />
<#else>
<#assign logo_css_class = logo_css_class + " custom-logo" />
</#if>
<#assign show_site_name_supported = getterUtil.getBoolean(theme_settings["show-site-name-supported"]!"", true) />
<#assign show_site_name_default = getterUtil.getBoolean(theme_settings["show-site-name-default"]!"", show_site_name_supported) />
<#assign show_site_name = getterUtil.getBoolean(layout.layoutSet.getSettingsProperty("showSiteName"), show_site_name_default) />
<#assign site_logo = company_logo />
<#assign logo_description = "" />
<#if !show_site_name>
<#assign logo_description = htmlUtil.escape(site_name) />
</#if>
<#-- ---------- Navigation ---------- -->
<#assign has_navigation = false />
<#if navItems??>
<#assign nav_items = navItems />
<#assign has_navigation = (nav_items?size > 0) />
</#if>
<#assign nav_css_class = "sort-pages modify-pages" />
<#if !has_navigation>
<#assign nav_css_class = nav_css_class + " hide" />
</#if>
<#-- ---------- My sites ---------- -->
<#assign show_my_sites = user.hasMySites() />
<#assign show_my_places = show_my_sites />
<#if show_my_sites>
<#assign my_sites_text = languageUtil.get(locale, "my-sites") />
<#assign my_places_text = my_sites_text />
</#if>
<#-- ---------- Includes ---------- -->
<#assign dir_include = "/html" />
<#assign body_bottom_include = "${dir_include}/common/themes/body_bottom.jsp" />
<#assign body_top_include = "${dir_include}/common/themes/body_top.jsp" />
<#assign bottom_include = "${dir_include}/common/themes/bottom.jsp" />
<#assign bottom_ext_include = bottom_include />
<#if tilesContent?has_content>
<#assign content_include = "${dir_include}${tilesContent}" />
</#if>
<#assign top_head_include = "${dir_include}/common/themes/top_head.jsp" />
<#assign top_messages_include = "${dir_include}/common/themes/top_messages.jsp" />
<#-- ---------- Date ---------- -->
<#assign date = dateUtil />
<#assign current_time = date.newDate() />
<#assign the_year = current_time?date?string("yyyy") />
<#-- ---------- Custom init ---------- -->
If you are still looking for new ones, you can define int_custom.ftl file;
These variables comes to context through Liferay code /portal-master/portal-impl/src/com/liferay/portal/template/TemplateContextHelper.java
variables.put("arrayUtil", ArrayUtil_IW.getInstance());
variables.put("auditMessageFactoryUtil",AuditMessageFactoryUtil.getAuditMessageFactory());
variables.put("auditRouterUtil", AuditRouterUtil.getAuditRouter());
variables.put( "browserSniffer", BrowserSnifferUtil.getBrowserSniffer());
variables.put("calendarFactory", CalendarFactoryUtil.getCalendarFactory());
variables.put("dateFormatFactory",FastDateFormatFactoryUtil.getFastDateFormatFactory());
variables.put("dateUtil", DateUtil_IW.getInstance());
variables.put("serviceLocator", serviceLocator);
variables.put("expandoColumnLocalService",serviceLocator.findService(ExpandoColumnLocalService.class.getName()));
variables.put("expandoRowLocalService",serviceLocator.findService(ExpandoRowLocalService.class.getName()));
variables.put("expandoTableLocalService",serviceLocator.findService(ExpandoTableLocalService.class.getName()));
variables.put("expandoValueLocalService",serviceLocator.findService(ExpandoValueLocalService.class.getName()));
variables.put("getterUtil", GetterUtil_IW.getInstance());
variables.put("htmlUtil", HtmlUtil.getHtml());
variables.put("httpUtil", HttpUtil.getHttp());
variables.put("imageToolUtil", ImageToolUtil.getImageTool());
variables.put("jsonFactoryUtil", JSONFactoryUtil.getJSONFactory());
variables.put("languageUtil", LanguageUtil.getLanguage());
variables.put("unicodeLanguageUtil",UnicodeLanguageUtil.getUnicodeLanguage());
variables.put("localeUtil", LocaleUtil.getInstance());
variables.put("paramUtil", ParamUtil_IW.getInstance());
variables.put("portalUtil", PortalUtil.getPortal());
variables.put("portal", PortalUtil.getPortal());
variables.put("prefsPropsUtil", PrefsPropsUtil.getPrefsProps());
variables.put("propsUtil", PropsUtil.getProps());
variables.put("portletModeFactory", PortletModeFactory_IW.getInstance());
variables.put("portletURLFactory",PortletURLFactoryUtil.getPortletURLFactory());
variables.put("utilLocator", utilLocator);
variables.put("saxReaderUtil",utilLocator.findUtil(SAXReader.class.getName()));
variables.put("sessionClicks", SessionClicks_IW.getInstance());
variables.put("staticFieldGetter", StaticFieldGetter.getInstance());
variables.put("stringUtil", StringUtil_IW.getInstance());
variables.put("timeZoneUtil", TimeZoneUtil_IW.getInstance());
variables.put("unicodeFormatter", UnicodeFormatter_IW.getInstance());
variables.put("validator", Validator_IW.getInstance());
variables.put("webServerToken", WebServerServletTokenUtil.getWebServerServletToken());
variables.put("windowStateFactory", WindowStateFactory_IW.getInstance());
variables.put("accountPermission",AccountPermissionUtil.getAccountPermission());
variables.put("commonPermission", CommonPermissionUtil.getCommonPermission());
variables.put("groupPermission", GroupPermissionUtil.getGroupPermission());
variables.put("layoutPermission", LayoutPermissionUtil.getLayoutPermission());
variables.put("organizationPermission", OrganizationPermissionUtil.getOrganizationPermission());
variables.put("passwordPolicyPermission",PasswordPolicyPermissionUtil.getPasswordPolicyPermission());
variables.put("portalPermission", PortalPermissionUtil.getPortalPermission());
variables.put("portletPermission",PortletPermissionUtil.getPortletPermission());
variables.put("portletProviderAction", portletProviderActionMap);
variables.put("rolePermission", RolePermissionUtil.getRolePermission());
variables.put("userGroupPermission",UserGroupPermissionUtil.getUserGroupPermission());
variables.put("userPermission", UserPermissionUtil.getUserPermission());
variables.put("dateFormats",FastDateFormatFactoryUtil.getFastDateFormatFactory());
variables.put("imageToken",WebServerServletTokenUtil.getWebServerServletToken());
variables.put("locationPermission", OrganizationPermissionUtil.getOrganizationPermission());
variables.put("randomizer", randomizer.getWrappedInstance());
