diff --git a/eeschema/CMakeLists.txt b/eeschema/CMakeLists.txt
index 1be2c291d1..e07d05e6e7 100644
--- a/eeschema/CMakeLists.txt
+++ b/eeschema/CMakeLists.txt
@@ -60,35 +60,48 @@ set( EESCHEMA_SCH_IO
 
     # HTTP IO plugin
     sch_io/http_lib/sch_io_http_lib.cpp
+    )
 
-    # Database IO plugin
-    sch_io/database/sch_io_database.cpp
-
-    # Eagle IO plugin
-    sch_io/eagle/sch_io_eagle.cpp
-
-    # Altium IO plugin
-    sch_io/altium/altium_parser_sch.cpp
-    sch_io/altium/sch_io_altium.cpp
-
-    # Cadstar IO plugin
-    sch_io/cadstar/cadstar_sch_archive_loader.cpp
-    sch_io/cadstar/cadstar_sch_archive_parser.cpp
-    sch_io/cadstar/sch_io_cadstar_archive.cpp
-
-    # LTSpice IO plugin
-    sch_io/ltspice/ltspice_schematic.cpp
-    sch_io/ltspice/sch_io_ltspice.cpp
-    sch_io/ltspice/sch_io_ltspice_parser.cpp
-
-    # EasyEDA IO plugin
-    sch_io/easyeda/sch_easyeda_parser.cpp
-    sch_io/easyeda/sch_io_easyeda.cpp
-
-    # EasyEDA Pro IO plugin
-    sch_io/easyedapro/sch_easyedapro_parser.cpp
-    sch_io/easyedapro/sch_io_easyedapro.cpp
+# Third-party importers and database plugin are not built for WASM:
+# - Database needs nanodbc/ODBC (common/database/database_connection.cpp
+#   is also gated on NOT EMSCRIPTEN in common/CMakeLists.txt).
+# - Altium pulls in pcbnew/pcb_io/altium common code which pcbnew itself
+#   excludes for WASM (third-party uses std::basic_string<unsigned short>
+#   that the current Emscripten libc++ rejects).
+# - Eagle/Cadstar/LTspice/EasyEDA are cross-tool importers we don't need
+#   for the MVP and they bring transitive incompatible dependencies in.
+# sch_io_mgr.cpp's factory cases are guarded with __EMSCRIPTEN__ to match.
+if( NOT EMSCRIPTEN )
+    list( APPEND EESCHEMA_SCH_IO
+        # Database IO plugin
+        sch_io/database/sch_io_database.cpp
+
+        # Eagle IO plugin
+        sch_io/eagle/sch_io_eagle.cpp
+
+        # Altium IO plugin
+        sch_io/altium/altium_parser_sch.cpp
+        sch_io/altium/sch_io_altium.cpp
+
+        # Cadstar IO plugin
+        sch_io/cadstar/cadstar_sch_archive_loader.cpp
+        sch_io/cadstar/cadstar_sch_archive_parser.cpp
+        sch_io/cadstar/sch_io_cadstar_archive.cpp
+
+        # LTSpice IO plugin
+        sch_io/ltspice/ltspice_schematic.cpp
+        sch_io/ltspice/sch_io_ltspice.cpp
+        sch_io/ltspice/sch_io_ltspice_parser.cpp
+
+        # EasyEDA IO plugin
+        sch_io/easyeda/sch_easyeda_parser.cpp
+        sch_io/easyeda/sch_io_easyeda.cpp
+
+        # EasyEDA Pro IO plugin
+        sch_io/easyedapro/sch_easyedapro_parser.cpp
+        sch_io/easyedapro/sch_io_easyedapro.cpp
     )
+endif()
 
 set( EESCHEMA_DLGS
     dialogs/dialog_annotate.cpp
@@ -276,6 +289,22 @@ set( EESCHEMA_SIM_SRCS
     widgets/tuner_slider_base.cpp
     )
 
+# WASM: the four largest BSIM/SOI/HSIM data initializer functions exceed the
+# V8/SpiderMonkey limit on locals per function ("too many locals") once
+# compiled. Replace them with empty stubs — the simulator UI is unreachable
+# in WASM anyway (see wasm/stubs/ngspice/sharedspice.h).
+if( EMSCRIPTEN )
+    list( REMOVE_ITEM EESCHEMA_SIM_SRCS
+        sim/sim_model_ngspice_data_bsim4.cpp
+        sim/sim_model_ngspice_data_b3soi.cpp
+        sim/sim_model_ngspice_data_b4soi.cpp
+        sim/sim_model_ngspice_data_hsim.cpp
+    )
+    list( APPEND EESCHEMA_SIM_SRCS
+        ${CMAKE_SOURCE_DIR}/../wasm/stubs/eeschema_ngspice_data_stubs.cpp
+    )
+endif()
+
 set( EESCHEMA_WIDGETS
     widgets/hierarchy_pane.cpp
     widgets/panel_sch_selection_filter_base.cpp
@@ -561,14 +590,25 @@ add_executable( eeschema WIN32 MACOSX_BUNDLE
     ${EESCHEMA_RESOURCES}
     )
 
-set_source_files_properties( ${CMAKE_SOURCE_DIR}/common/single_top.cpp PROPERTIES
-    COMPILE_DEFINITIONS "TOP_FRAME=FRAME_SCH;PGM_DATA_FILE_EXT=\"kicad_sch\";BUILD_KIWAY_DLL"
-    )
+if( EMSCRIPTEN )
+    # WASM: Static kiface linking - don't define BUILD_KIWAY_DLL
+    set_source_files_properties( ${CMAKE_SOURCE_DIR}/common/single_top.cpp PROPERTIES
+        COMPILE_DEFINITIONS "TOP_FRAME=FRAME_SCH;PGM_DATA_FILE_EXT=\"kicad_sch\""
+        )
+else()
+    set_source_files_properties( ${CMAKE_SOURCE_DIR}/common/single_top.cpp PROPERTIES
+        COMPILE_DEFINITIONS "TOP_FRAME=FRAME_SCH;PGM_DATA_FILE_EXT=\"kicad_sch\";BUILD_KIWAY_DLL"
+        )
+endif()
 
-target_link_libraries( eeschema
-    kicommon
-    ${wxWidgets_LIBRARIES}
-    )
+if( NOT EMSCRIPTEN )
+    # Native: minimal link, kiface loaded dynamically
+    target_link_libraries( eeschema
+        kicommon
+        ${wxWidgets_LIBRARIES}
+        )
+endif()
+# WASM linking is done after EESCHEMA_KIFACE_LIBRARIES is defined
 
 # the main Eeschema program, in DSO form.
 add_library( eeschema_kiface_objects OBJECT
@@ -577,6 +617,15 @@ add_library( eeschema_kiface_objects OBJECT
     ${EESCHEMA_COMMON_SRCS}
     )
 
+# WASM: Bring eeschema.cpp (the KIFACE entry point) and stub sources into the
+# kiface_objects translation unit so static linking finds KIFACE_GETTER.
+if( EMSCRIPTEN )
+    target_sources( eeschema_kiface_objects PRIVATE
+        eeschema.cpp
+        ${CMAKE_SOURCE_DIR}/../wasm/stubs/eeschema_frame_stub.cpp
+    )
+endif()
+
 if( KICAD_USE_PCH )
     target_precompile_headers( eeschema_kiface_objects
         PRIVATE
@@ -612,21 +661,49 @@ target_link_libraries( eeschema_kiface_objects PUBLIC eeschema_navlib)
 
 add_dependencies( eeschema_kiface_objects eeschema_navlib )
 
-add_library( eeschema_kiface MODULE
-    eeschema.cpp
+if( EMSCRIPTEN )
+    # WASM: empty MODULE - eeschema.cpp was hoisted into kiface_objects above
+    # so the executable can link KIFACE_GETTER statically. The empty MODULE
+    # target is kept so post-build steps that reference it still resolve.
+    add_library( eeschema_kiface MODULE )
+else()
+    add_library( eeschema_kiface MODULE
+        eeschema.cpp
+        )
+endif()
+
+set( EESCHEMA_KIFACE_LIBRARIES
+    eeschema_kiface_objects
+    common
+    eeschema_navlib
+    kicommon
+    kiplatform
+    gal
+    scripting
+    sexpr
+    core
+    markdown_lib
+    ${wxWidgets_LIBRARIES}
+    ${NGSPICE_LIBRARY}
+    Boost::headers
     )
 
+# WASM: Link kiface objects directly into eeschema executable (static linking)
+if( EMSCRIPTEN )
+    target_link_libraries( eeschema
+        PRIVATE
+            ${EESCHEMA_KIFACE_LIBRARIES}
+        )
+    # WASM: Allow multiple definitions of symbols that exist in both
+    # KiCad and wxWidgets (matches the pcbnew WASM pattern).
+    target_link_options( eeschema PRIVATE
+        "LINKER:--allow-multiple-definition"
+        )
+endif()
+
 target_link_libraries( eeschema_kiface
     PRIVATE
-        common
-        eeschema_kiface_objects
-        markdown_lib
-        scripting
-        sexpr
-        core
-        Boost::headers
-        ${wxWidgets_LIBRARIES}
-        ${NGSPICE_LIBRARY}
+        ${EESCHEMA_KIFACE_LIBRARIES}
     )
 
 if( MSVC )
@@ -649,9 +726,17 @@ set_target_properties( eeschema_kiface PROPERTIES
     )
 
 # The KIFACE is in eeschema.cpp, export it:
-set_source_files_properties( eeschema.cpp PROPERTIES
-    COMPILE_DEFINITIONS     "BUILD_KIWAY_DLL;COMPILING_DLL"
-    )
+if( EMSCRIPTEN )
+    # WASM: Static linking - don't define BUILD_KIWAY_DLL so KIFACE_GETTER
+    # is exported with its statically-linkable name (KIFACE_1).
+    set_source_files_properties( eeschema.cpp PROPERTIES
+        COMPILE_DEFINITIONS     "COMPILING_DLL"
+        )
+else()
+    set_source_files_properties( eeschema.cpp PROPERTIES
+        COMPILE_DEFINITIONS     "BUILD_KIWAY_DLL;COMPILING_DLL"
+        )
+endif()
 
 # if building eeschema, then also build eeschema_kiface if out of date.
 add_dependencies( eeschema eeschema_kiface )
diff --git a/eeschema/dialogs/dialog_sim_command.cpp b/eeschema/dialogs/dialog_sim_command.cpp
index 7ec105f35a..19fa35d460 100644
--- a/eeschema/dialogs/dialog_sim_command.cpp
+++ b/eeschema/dialogs/dialog_sim_command.cpp
@@ -570,7 +570,7 @@ void DIALOG_SIM_COMMAND::updateDCSources( wxChar aType, wxChoice* aSource )
 {
     wxString prevSelection;
 
-    if( !aSource->IsEmpty() && aSource->GetSelection() >= 0 )
+    if( aSource->GetCount() > 0 && aSource->GetSelection() >= 0 )
         prevSelection = aSource->GetString( aSource->GetSelection() );
 
     std::set<wxString> sourcesList;
diff --git a/eeschema/eeschema.cpp b/eeschema/eeschema.cpp
index f3b334d1c8..d56ca181dc 100644
--- a/eeschema/eeschema.cpp
+++ b/eeschema/eeschema.cpp
@@ -201,7 +201,13 @@ static struct IFACE : public KIFACE_BASE, public UNITS_PROVIDER
         }
 
         case FRAME_SCH_SYMBOL_EDITOR:
+#ifdef __EMSCRIPTEN__
+            // WASM build: symbol library editor is not supported (see
+            // features/schematic/0001-eeschema-iface-stubs.md).
+            return nullptr;
+#else
             return new SYMBOL_EDIT_FRAME( aKiway, aParent );
+#endif
 
         case FRAME_SIMULATOR:
         {
@@ -219,10 +225,19 @@ static struct IFACE : public KIFACE_BASE, public UNITS_PROVIDER
         }
 
         case FRAME_SCH_VIEWER:
+#ifdef __EMSCRIPTEN__
+            // WASM build: symbol viewer is not supported.
+            return nullptr;
+#else
             return new SYMBOL_VIEWER_FRAME( aKiway, aParent );
+#endif
 
         case FRAME_SYMBOL_CHOOSER:
         {
+#ifdef __EMSCRIPTEN__
+            // WASM build: symbol chooser is not supported (no bundled libs).
+            return nullptr;
+#else
             bool cancelled = false;
             SYMBOL_CHOOSER_FRAME* chooser = new SYMBOL_CHOOSER_FRAME( aKiway, aParent, cancelled );
 
@@ -233,6 +248,7 @@ static struct IFACE : public KIFACE_BASE, public UNITS_PROVIDER
             }
 
             return chooser;
+#endif
         }
 
         case DIALOG_SCH_LIBRARY_TABLE:
diff --git a/eeschema/sch_base_frame.cpp b/eeschema/sch_base_frame.cpp
index 161379a699..e722b7a043 100644
--- a/eeschema/sch_base_frame.cpp
+++ b/eeschema/sch_base_frame.cpp
@@ -775,6 +775,7 @@ wxString SCH_BASE_FRAME::SelectLibrary( const wxString& aDialogTitle, const wxSt
 
 void SCH_BASE_FRAME::setSymWatcher( const LIB_ID* aID )
 {
+#if wxUSE_FSWATCHER
     Unbind( wxEVT_FSWATCHER, &SCH_BASE_FRAME::OnSymChange, this );
 
     if( m_watcher )
@@ -824,11 +825,15 @@ void SCH_BASE_FRAME::setSymWatcher( const LIB_ID* aID )
         wxLogNull silence;
         m_watcher->Add( fn );
     }
+#else
+    (void) aID;
+#endif
 }
 
 
 void SCH_BASE_FRAME::OnSymChange( wxFileSystemWatcherEvent& aEvent )
 {
+#if wxUSE_FSWATCHER
     LEGACY_SYMBOL_LIBS* libs = PROJECT_SCH::LegacySchLibs( &Prj() );
 
     wxLogTrace( traceLibWatch, "OnSymChange: %s, watcher file: %s",
@@ -846,6 +851,9 @@ void SCH_BASE_FRAME::OnSymChange( wxFileSystemWatcherEvent& aEvent )
         wxLogTrace( traceLibWatch, "Failed to start the debounce timer" );
         return;
     }
+#else
+    (void) aEvent;
+#endif
 }
 
 
diff --git a/eeschema/sch_base_frame.h b/eeschema/sch_base_frame.h
index 2d701c7d28..a86ae37237 100644
--- a/eeschema/sch_base_frame.h
+++ b/eeschema/sch_base_frame.h
@@ -323,7 +323,9 @@ protected:
 private:
 
     /// These are file watchers for the symbol library tables.
+#if wxUSE_FSWATCHER
     std::unique_ptr<wxFileSystemWatcher>    m_watcher;
+#endif
     wxFileName                              m_watcherFileName;
     wxDateTime                              m_watcherLastModified;
     wxTimer                                 m_watcherDebounceTimer;
diff --git a/eeschema/sch_edit_frame.cpp b/eeschema/sch_edit_frame.cpp
index fd5a91a388..6eab185446 100644
--- a/eeschema/sch_edit_frame.cpp
+++ b/eeschema/sch_edit_frame.cpp
@@ -56,7 +56,9 @@
 #include <core/profile.h>
 #include <project/project_file.h>
 #include <project/net_settings.h>
+#ifdef KICAD_SCRIPTING
 #include <python_scripting.h>
+#endif
 #include <sch_edit_frame.h>
 #include <symbol_chooser_frame.h>
 #include <sch_painter.h>
diff --git a/eeschema/sch_io/sch_io_mgr.cpp b/eeschema/sch_io/sch_io_mgr.cpp
index 63e55bcdae..922fef0d90 100644
--- a/eeschema/sch_io/sch_io_mgr.cpp
+++ b/eeschema/sch_io/sch_io_mgr.cpp
@@ -24,17 +24,22 @@
 #include <wx/uri.h>
 
 #include <sch_io/sch_io_mgr.h>
-#include <sch_io/eagle/sch_io_eagle.h>
 #include <sch_io/kicad_legacy/sch_io_kicad_legacy.h>
 #include <sch_io/kicad_sexpr/sch_io_kicad_sexpr.h>
+#include <sch_io/http_lib/sch_io_http_lib.h>
 
+// Third-party importers and the database plugin are excluded from the WASM
+// build (see kicad/eeschema/CMakeLists.txt). Their FindPlugin cases below
+// return nullptr on WASM.
+#ifndef __EMSCRIPTEN__
+#include <sch_io/eagle/sch_io_eagle.h>
 #include <sch_io/altium/sch_io_altium.h>
 #include <sch_io/cadstar/sch_io_cadstar_archive.h>
 #include <sch_io/easyeda/sch_io_easyeda.h>
 #include <sch_io/easyedapro/sch_io_easyedapro.h>
 #include <sch_io/database/sch_io_database.h>
 #include <sch_io/ltspice/sch_io_ltspice.h>
-#include <sch_io/http_lib/sch_io_http_lib.h>
+#endif
 #include <common.h>     // for ExpandEnvVarSubstitutions
 
 #include <wildcards_and_files_ext.h>
@@ -68,6 +73,8 @@ SCH_IO* SCH_IO_MGR::FindPlugin( SCH_FILE_T aFileType )
     {
     case SCH_KICAD:           return new SCH_IO_KICAD_SEXPR();
     case SCH_LEGACY:          return new SCH_IO_KICAD_LEGACY();
+    case SCH_HTTP:            return new SCH_IO_HTTP_LIB();
+#ifndef __EMSCRIPTEN__
     case SCH_ALTIUM:          return new SCH_IO_ALTIUM();
     case SCH_CADSTAR_ARCHIVE: return new SCH_IO_CADSTAR_ARCHIVE();
     case SCH_DATABASE:        return new SCH_IO_DATABASE();
@@ -75,7 +82,7 @@ SCH_IO* SCH_IO_MGR::FindPlugin( SCH_FILE_T aFileType )
     case SCH_EASYEDA:         return new SCH_IO_EASYEDA();
     case SCH_EASYEDAPRO:      return new SCH_IO_EASYEDAPRO();
     case SCH_LTSPICE:         return new SCH_IO_LTSPICE();
-    case SCH_HTTP:            return new SCH_IO_HTTP_LIB();
+#endif
     default:                  return nullptr;
     }
 }
diff --git a/eeschema/toolbars_sch_editor.cpp b/eeschema/toolbars_sch_editor.cpp
index 600f4379bc..a4df373475 100644
--- a/eeschema/toolbars_sch_editor.cpp
+++ b/eeschema/toolbars_sch_editor.cpp
@@ -32,7 +32,9 @@
 #include <bitmaps.h>
 #include <eeschema_id.h>
 #include <pgm_base.h>
+#ifdef KICAD_SCRIPTING
 #include <python_scripting.h>
+#endif
 #include <tool/tool_manager.h>
 #include <tool/action_toolbar.h>
 #include <tools/sch_actions.h>
@@ -251,7 +253,11 @@ void SCH_EDIT_FRAME::configureToolbars()
         [this]( ACTION_TOOLBAR* aToolbar )
         {
             // Add scripting console and API plugins
+            #ifdef KICAD_SCRIPTING
             bool scriptingAvailable = SCRIPTING::IsWxAvailable();
+            #else
+            bool scriptingAvailable = false;
+            #endif
 
             #ifdef KICAD_IPC_API
             bool haveApiPlugins = Pgm().GetCommonSettings()->m_Api.enable_server &&