diff --git a/boards.txt b/boards.txt
index 798564387..36a536090 100644
--- a/boards.txt
+++ b/boards.txt
@@ -72,6 +72,9 @@ giga.debug.server.openocd.scripts.2=target/stm32h7x_dual_bank.cfg
 giga.debug.cortex-debug.custom.request=attach
 giga.debug.svd_file={runtime.platform.path}/svd/STM32H747_CM7.svd
 
+giga.build.ota.magic=0x23410266
+giga.build.ota.sketch_offset=0xA0000
+
 ##########################################################################################
 
 nano33ble.name=Arduino Nano 33 BLE
@@ -256,6 +259,9 @@ portentah7.bootloader.interface=0
 portentah7.bootloader.file=zephyr-{build.variant}.bin
 portentah7.bootloader.address=0x08040000
 
+portentah7.build.ota.magic=0x2341025B
+portentah7.build.ota.sketch_offset=0xA0000
+
 portentah7.debug.tool=gdb
 portentah7.debug.server.openocd.scripts.0=interface/{programmer.protocol}.cfg
 portentah7.debug.server.openocd.scripts.1={programmer.transport_script}
@@ -308,6 +314,9 @@ nicla_vision.bootloader.interface=0
 nicla_vision.bootloader.file=zephyr-{build.variant}.bin
 nicla_vision.bootloader.address=0x08040000
 
+nicla_vision.build.ota.magic=0x2341025F
+nicla_vision.build.ota.sketch_offset=0xA0000
+
 nicla_vision.debug.tool=gdb
 nicla_vision.debug.server.openocd.scripts.0=interface/{programmer.protocol}.cfg
 nicla_vision.debug.server.openocd.scripts.1={programmer.transport_script}
@@ -445,9 +454,12 @@ portentac33.upload.wait_for_upload_port=false
 portentac33.upload.native_usb=true
 portentac33.upload.dfuse=
 
+portentac33.sfu.file=loader/blobs/c33_sfu.bin
+portentac33.sfu.size=0x20000
+
 portentac33.bootloader.tool=dfu-util
 portentac33.bootloader.tool.default=dfu-util
-portentac33.bootloader.file=zephyr-{build.variant}.bin
+portentac33.bootloader.file=zephyr-{build.variant}-sfu.bin
 portentac33.bootloader.interface=0
 portentac33.bootloader.address=0x10000
 portentac33.bootloader.pid=0x0368
@@ -458,6 +470,9 @@ portentac33.leave.dfuse={empty} -Q
 portentac33.loader.args.with_sketch={empty} -w
 portentac33.sketch.args.without_loader={empty} -w
 
+portentac33.build.ota.magic=0x23410068
+portentac33.build.ota.sketch_offset=0xF0000
+
 ##########################################################################################
 
 opta.name=Arduino Opta
@@ -510,6 +525,9 @@ opta.debug.server.openocd.scripts.2=target/stm32h7x_dual_bank.cfg
 opta.debug.cortex-debug.custom.request=attach
 opta.debug.svd_file={runtime.platform.path}/svd/STM32H747_CM7.svd
 
+opta.build.ota.magic=0x23410064
+opta.build.ota.sketch_offset=0xA0000
+
 ##########################################################################################
 
 nano_matter.name=Arduino Nano Matter
diff --git a/cores/arduino/llext_wrappers.c b/cores/arduino/llext_wrappers.c
index 0ea624939..8168076c8 100644
--- a/cores/arduino/llext_wrappers.c
+++ b/cores/arduino/llext_wrappers.c
@@ -109,6 +109,7 @@ W2(char *, strstr, const char *, const char *)
 W2(int, strcmp, const char *, const char *)
 W3(int, strncmp, const char *, const char *, size_t)
 W2(int, strcasecmp, const char *, const char *)
+W3(int, strncasecmp, const char *, const char *, size_t)
 W3(char *, strncpy, char *, const char *, size_t)
 W2(char *, strcat, char *, const char *)
 W2(char *, strcpy, char *, const char *)
@@ -216,6 +217,7 @@ VN(__aeabi_fcmpun)
 VN(__aeabi_d2iz)
 VN(__aeabi_d2uiz)
 VN(__aeabi_d2lz)
+VN(__aeabi_d2ulz)
 VN(__aeabi_i2d)
 VN(__aeabi_ui2d)
 VN(__aeabi_l2d)
diff --git a/cores/arduino/ota_api.h b/cores/arduino/ota_api.h
new file mode 100644
index 000000000..e97bf3460
--- /dev/null
+++ b/cores/arduino/ota_api.h
@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifdef CONFIG_OTA
+
+#include "../../loader/ota/ota_api.h"
+
+#endif // CONFIG_OTA
diff --git a/extra/build.sh b/extra/build.sh
index 4678b134a..cbaf42cf6 100755
--- a/extra/build.sh
+++ b/extra/build.sh
@@ -57,6 +57,10 @@ if ! [ -z "$chosen_board" ]; then
 	if [ x$2 == x"--debug" ]; then
 		args+=(-- -DEXTRA_CONF_FILE=../extra/debug.conf)
 	fi
+
+	# check if the board requires to prepend a second stage bootloader to the loader
+	sfu_file=$(jq -cr '.sfu_file' <<< "$chosen_board")
+	sfu_size=$(jq -cr '.sfu_size' <<< "$chosen_board")
 else
 	# expect Zephyr-compatible target and args
 	target=$1
@@ -125,6 +129,17 @@ done
 cp ${BUILD_DIR}/zephyr/zephyr.dts firmwares/zephyr-$variant.dts
 cp ${BUILD_DIR}/zephyr/.config firmwares/zephyr-$variant.config
 
+# Some boards, like the C33, need a second stage bootloader to enable OTA upgrades,
+# if the file is specified in boards.txt under .sfu.file, prepend it to the loader binary into a
+# firmwares/zephyr-$variant-sfu.bin file.
+# this file needs to be specified in bootloader.file=zephyr-{build.variant}-sfu.bin
+if [ "$sfu_file" ] ; then
+    dd if=${sfu_file} of=firmwares/zephyr-$variant-sfu.bin conv=notrunc status=none
+
+    offset=$(printf "%d" "${sfu_size}")
+    dd if=firmwares/zephyr-$variant.bin of=firmwares/zephyr-$variant-sfu.bin bs=1 seek=${offset} conv=notrunc status=none
+fi
+
 # Generate the provides.ld file for linked builds
 echo "Generating exported symbol scripts"
 extra/gen_provides.py "${BUILD_DIR}/zephyr/zephyr.elf" -T > ${VARIANT_DIR}/tls-syms.S
diff --git a/extra/get_board_details.sh b/extra/get_board_details.sh
index a70d8b8b0..94efb8696 100755
--- a/extra/get_board_details.sh
+++ b/extra/get_board_details.sh
@@ -24,6 +24,8 @@ for BOARD in $(get_boards); do
 	ARTIFACT=$(get_board_field $BOARD "build\\.artifact")
 	ARTIFACT=${ARTIFACT:-zephyr_contrib}
 	UPLOAD_OFFSET=$(get_board_field $BOARD "upload\\.offset")
+	SFU_FILE=$(get_board_field $BOARD "sfu\\.file")
+	SFU_SIZE=$(get_board_field $BOARD "sfu\\.size")
 
 	ARTIFACT_JSON=extra/artifacts/$ARTIFACT.json
 	if ! [ -f "$ARTIFACT_JSON" ] ; then
@@ -51,7 +53,9 @@ for BOARD in $(get_boards); do
 	  "hals": "$HALS",
 	  "artifact": "$ARTIFACT",
 	  "subarch": "$SUBARCH",
-	  "upload_offset": "$UPLOAD_OFFSET"
+	  "upload_offset": "$UPLOAD_OFFSET",
+	  "sfu_file": "$SFU_FILE",
+	  "sfu_size": "$SFU_SIZE"
 	}
 EOF
 done | jq -crs .
diff --git a/loader/CMakeLists.txt b/loader/CMakeLists.txt
index 5e6f2c9f2..d132ba12d 100644
--- a/loader/CMakeLists.txt
+++ b/loader/CMakeLists.txt
@@ -18,6 +18,7 @@ find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(app LANGUAGES C CXX)
 
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/blobs)
+add_subdirectory_ifdef(CONFIG_OTA ${CMAKE_CURRENT_SOURCE_DIR}/ota)
 
 # Memory region relocation based on Kconfig
 # Relocate LLEXT heap if region specified
@@ -44,3 +45,4 @@ target_compile_definitions(app PUBLIC _XOPEN_SOURCE=700)
 target_compile_definitions(app PUBLIC _GNU_SOURCE)
 
 target_link_libraries(app PUBLIC blobs)
+target_link_libraries_ifdef(CONFIG_OTA app PUBLIC ota)
diff --git a/loader/Kconfig b/loader/Kconfig
index 9965f3757..31b291958 100644
--- a/loader/Kconfig
+++ b/loader/Kconfig
@@ -23,3 +23,5 @@ config MAIN_STACK_REGION
 	depends on CODE_DATA_RELOCATION
 	help
 	  Specify the memory region for main stack.
+
+rsource "ota/Kconfig"
diff --git a/loader/blobs/c33_sfu.bin b/loader/blobs/c33_sfu.bin
new file mode 100644
index 000000000..52732e055
Binary files /dev/null and b/loader/blobs/c33_sfu.bin differ
diff --git a/loader/llext_exports.c b/loader/llext_exports.c
index 4c2c6e8a9..587b41950 100644
--- a/loader/llext_exports.c
+++ b/loader/llext_exports.c
@@ -8,6 +8,7 @@
 #include <strings.h>
 #include <zephyr/llext/symbol.h>
 #include <zephyr/usb/usb_device.h>
+#include <zephyr/sys/reboot.h>
 #include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -53,6 +54,7 @@ EXPORT_LIBC_SYM(strstr);
 EXPORT_LIBC_SYM(strncmp);
 EXPORT_LIBC_SYM(strncpy);
 EXPORT_LIBC_SYM(strcasecmp);
+EXPORT_LIBC_SYM(strncasecmp);
 EXPORT_LIBC_SYM(strcmp);
 EXPORT_LIBC_SYM(strlen);
 EXPORT_LIBC_SYM(strnlen);
@@ -349,6 +351,7 @@ EXPORT_LIBC_SYM(gettimeofday);
 #endif
 
 EXPORT_SYMBOL(sys_clock_settime);
+
 EXPORT_SYMBOL(mktime);
 EXPORT_SYMBOL(gmtime);
 
@@ -409,6 +412,7 @@ EXPORT_AEABI_SYM(__aeabi_fcmpun);
 EXPORT_AEABI_SYM(__aeabi_d2iz);
 EXPORT_AEABI_SYM(__aeabi_d2uiz);
 EXPORT_AEABI_SYM(__aeabi_d2lz);
+EXPORT_AEABI_SYM(__aeabi_d2ulz);
 EXPORT_AEABI_SYM(__aeabi_i2d);
 EXPORT_AEABI_SYM(__aeabi_ui2d);
 EXPORT_AEABI_SYM(__aeabi_l2d);
diff --git a/loader/main.c b/loader/main.c
index 0947559ea..c8fa42fa2 100644
--- a/loader/main.c
+++ b/loader/main.c
@@ -24,6 +24,7 @@ LOG_MODULE_REGISTER(sketch);
 
 #include <zephyr/devicetree/fixed-partitions.h>
 #include "../cores/arduino/zephyr_sketch_header.h"
+#include "ota/ota_sketch_check.h"
 
 #define SKETCH_RAM_BUFFER_LEN 131072
 
@@ -136,6 +137,10 @@ static int loader(const struct shell *sh) {
 		return rc;
 	}
 
+#if defined(CONFIG_OTA)
+	try_ota_update(fa);
+#endif
+
 	uintptr_t base_addr = DT_PARTITION_ADDR(DT_NODELABEL(user_sketch));
 
 	char header[SKETCH_HEADER_LEN];
diff --git a/loader/ota/CMakeLists.txt b/loader/ota/CMakeLists.txt
new file mode 100644
index 000000000..079b7c8b2
--- /dev/null
+++ b/loader/ota/CMakeLists.txt
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_interface_library_named(ota)
+
+target_sources(app PRIVATE ${CMAKE_CURRENT_LIST_DIR}/ota_sketch_check.c)
+target_sources(app PRIVATE ${CMAKE_CURRENT_LIST_DIR}/ota_llext_exports.c)
+zephyr_include_directories(${CMAKE_CURRENT_LIST_DIR})
+
+target_sources_ifdef(CONFIG_BOARD_ARDUINO_PORTENTA_C33 app PRIVATE
+    ${CMAKE_CURRENT_LIST_DIR}/ota_portentac33.c)
+
+target_sources_ifdef(CONFIG_SOC_SERIES_STM32H7X app PRIVATE
+    ${CMAKE_CURRENT_LIST_DIR}/ota_arduino_stm32h7.c)
+
+target_sources(app PRIVATE ${CMAKE_CURRENT_LIST_DIR}/ota_sketch.c)
diff --git a/loader/ota/Kconfig b/loader/ota/Kconfig
new file mode 100644
index 000000000..89b68bc63
--- /dev/null
+++ b/loader/ota/Kconfig
@@ -0,0 +1,58 @@
+#
+# Copyright (c) Arduino s.r.l. and/or its affiliated companies
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+menuconfig OTA
+	bool "Enable lookup for sketch update at boot"
+	depends on FILE_SYSTEM
+	select REBOOT
+	select RTC if SOC_SERIES_STM32H7X
+	default n
+	help
+	  Enable checking for an update inside of the filesystem. If a file inside of
+	  OTA_SKETCH_UPDATE_PATH is found during the boot, the OTA procedure is started and the
+	  current sketch binary is replaced
+
+if OTA
+
+config OTA_SKETCH_UPDATE_PATH
+	string "The path it is looked for ota"
+	default "/ota:/UPDATE_SKETCH.BIN"
+	help
+	  the path that is checked for a sketch new binary
+
+config OTA_SKETCH_TEMP_PATH_POSTFIX
+	string "temporary file name postfix for sketch ota not ready"
+	default ".TEMP"
+	help
+	  String that is appended to sketch ota filename when it is still not ready to be loaded,
+	  a rename operation is required to make the ota file enabled for next reboot
+
+config OTA_LOADER_UPDATE_PATH
+	string "The path it is looked for ota"
+	default "/ota:/UPDATE.BIN"
+	help
+	  the path that is checked for the loader new binary
+
+config OTA_LOADER_TEMP_PATH_POSTFIX
+	string "temporary file name postfix for loader ota not ready"
+	default "" if SOC_SERIES_STM32H7X
+	default ".TEMP"
+	help
+	  String that is appended to loader ota filename when it is still not ready to be loaded,
+	  a rename operation is required to make the ota file enabled for next reboot
+
+config OTA_TRANSCRIPTION_CHUNK_SIZE
+	int "The size of the stack allocated chunk in bytes for transcription"
+	default 1024
+	help
+	  The size of the stack allocated chunk in bytes for ota file transcription
+
+module = OTA
+module-str = OTA
+module-help = Sets log level for OTA
+source "subsys/logging/Kconfig.template.log_config"
+
+endif
diff --git a/loader/ota/ota_api.h b/loader/ota/ota_api.h
new file mode 100644
index 000000000..d84ecc029
--- /dev/null
+++ b/loader/ota/ota_api.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/device.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define OTA_SKETCH_FILENAME CONFIG_OTA_SKETCH_UPDATE_PATH CONFIG_OTA_SKETCH_TEMP_PATH_POSTFIX
+#define OTA_LOADER_FILENAME CONFIG_OTA_LOADER_UPDATE_PATH CONFIG_OTA_LOADER_TEMP_PATH_POSTFIX
+
+int ota_sketch_ready();
+int ota_sketch_start();
+
+int ota_loader_ready();
+int ota_loader_start();
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/loader/ota/ota_arduino_stm32h7.c b/loader/ota/ota_arduino_stm32h7.c
new file mode 100644
index 000000000..739ae02af
--- /dev/null
+++ b/loader/ota/ota_arduino_stm32h7.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "ota_api.h"
+#include <zephyr/fs/fs.h>
+#include <zephyr/sys/reboot.h>
+#include <stm32h7xx_ll_rtc.h>
+#include <stm32_backup_domain.h>
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(ota_loader, CONFIG_OTA_LOG_LEVEL);
+
+#define OTA_MAGIC_BOOT   0x07AA
+// #define OTA_STORAGE_TYPE 0xA4   // QSPI_FLASH | FATFS | MBR
+#define OTA_STORAGE_TYPE ((1 << 2) | (1 << 5) | (1 << 7))
+#define OTA_MBR_PART     2
+
+int ota_loader_ready() {
+	struct fs_dirent entry;
+	int ret;
+
+	if (fs_stat(OTA_LOADER_FILENAME, &entry) < 0) {
+		LOG_WRN("tried to perform an ota without binary present");
+		return -1;
+	}
+
+	if (sizeof(CONFIG_OTA_LOADER_TEMP_PATH_POSTFIX) > 1) {
+		ret = fs_rename(OTA_LOADER_FILENAME, CONFIG_OTA_LOADER_UPDATE_PATH);
+		if (ret < 0) {
+			LOG_ERR("unable to rename ota file: %d", ret);
+			return ret;
+		}
+	}
+
+	stm32_backup_domain_enable_access();
+	LL_RTC_BAK_SetRegister(RTC, RTC_BKP_DR0, OTA_MAGIC_BOOT);
+	LL_RTC_BAK_SetRegister(RTC, RTC_BKP_DR1, OTA_STORAGE_TYPE);
+	LL_RTC_BAK_SetRegister(RTC, RTC_BKP_DR2, OTA_MBR_PART);
+	LL_RTC_BAK_SetRegister(RTC, RTC_BKP_DR3, entry.size);
+	stm32_backup_domain_disable_access();
+
+	LOG_INF("OTA marked as ready");
+
+	return 0;
+}
+
+int ota_loader_start() {
+	LOG_INF("OTA started, reboot in progress");
+
+	sys_reboot(SYS_REBOOT_COLD);
+	return 0; // unreachable
+}
diff --git a/loader/ota/ota_llext_exports.c b/loader/ota/ota_llext_exports.c
new file mode 100644
index 000000000..39947fc4e
--- /dev/null
+++ b/loader/ota/ota_llext_exports.c
@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "ota_api.h"
+#include <zephyr/llext/symbol.h>
+
+EXPORT_SYMBOL(ota_sketch_ready);
+EXPORT_SYMBOL(ota_sketch_start);
+
+EXPORT_SYMBOL(ota_loader_ready);
+EXPORT_SYMBOL(ota_loader_start);
diff --git a/loader/ota/ota_portentac33.c b/loader/ota/ota_portentac33.c
new file mode 100644
index 000000000..335f6fbc1
--- /dev/null
+++ b/loader/ota/ota_portentac33.c
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "ota_api.h"
+
+#include <zephyr/fs/fs.h>
+#include <zephyr/sys/reboot.h>
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(ota_loader, CONFIG_OTA_LOG_LEVEL);
+
+int ota_loader_ready() {
+	// C33: SFU checks for UPDATE.BIN.OTA on every boot — no action needed
+	struct fs_dirent entry;
+	int ret;
+
+	if (fs_stat(OTA_LOADER_FILENAME, &entry) < 0) {
+		LOG_WRN("tried to perform an ota without binary present");
+		return -1;
+	}
+
+	if (sizeof(CONFIG_OTA_LOADER_TEMP_PATH_POSTFIX) > 1) {
+		ret = fs_rename(OTA_LOADER_FILENAME, CONFIG_OTA_LOADER_UPDATE_PATH);
+
+		if (ret < 0) {
+			LOG_ERR("unable to rename ota file: %d", ret);
+		}
+	}
+
+	LOG_INF("OTA marked as ready");
+	return ret;
+}
+
+int ota_loader_start() {
+	sys_reboot(SYS_REBOOT_COLD);
+
+	return 0; // unreachable
+}
diff --git a/loader/ota/ota_sketch.c b/loader/ota/ota_sketch.c
new file mode 100644
index 000000000..6014b737e
--- /dev/null
+++ b/loader/ota/ota_sketch.c
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/fs/fs.h>
+#include <zephyr/sys/reboot.h>
+
+#include "ota_api.h"
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(ota_sketch, CONFIG_OTA_LOG_LEVEL);
+
+int ota_sketch_ready() {
+	struct fs_dirent entry;
+	int ret;
+
+	if (fs_stat(OTA_SKETCH_FILENAME, &entry) < 0) {
+		LOG_WRN("tried to perform an ota without binary present");
+		return -1;
+	}
+
+	if (sizeof(CONFIG_OTA_SKETCH_TEMP_PATH_POSTFIX) > 1) {
+		ret = fs_rename(OTA_SKETCH_FILENAME, CONFIG_OTA_SKETCH_UPDATE_PATH);
+
+		if (ret < 0) {
+			LOG_ERR("unable to rename ota file: %d", ret);
+		}
+	}
+
+	LOG_INF("OTA marked as ready");
+
+	return ret;
+}
+
+int ota_sketch_start() {
+	LOG_INF("OTA started, reboot in progress");
+
+	sys_reboot(SYS_REBOOT_COLD);
+	return 0;
+}
diff --git a/loader/ota/ota_sketch_check.c b/loader/ota/ota_sketch_check.c
new file mode 100644
index 000000000..dced0c415
--- /dev/null
+++ b/loader/ota/ota_sketch_check.c
@@ -0,0 +1,194 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_REGISTER(ota, CONFIG_OTA_LOG_LEVEL);
+
+#include "ota_sketch_check.h"
+#include "../../cores/arduino/zephyr_sketch_header.h"
+
+#include <zephyr/fs/fs.h>
+#include <string.h>
+#include <zephyr/drivers/flash.h>
+
+#include <assert.h>
+
+static int verify_sketch_header(const struct flash_area *fa, const struct sketch_header_v1 *hdr,
+								struct fs_dirent *entry) {
+	int rc = 0;
+
+	LOG_DBG("Header ver: %02x, len: %d, magic: %04x, flags: %02X", hdr->ver, hdr->len, hdr->magic,
+			hdr->flags);
+
+	if (sketch_header_v1_verify(hdr) != 0) {
+		LOG_ERR("invalid sketch header (ver=0x%x magic=0x%x)", hdr->ver, hdr->magic);
+		return -1;
+	}
+
+	LOG_INF("sketch length = %u bytes", (unsigned)hdr->len);
+
+	/* Bounds-check before the destructive erase. */
+	if (hdr->len > fa->fa_size) {
+		LOG_ERR("sketch too large for partition (%u > %u)", (unsigned)hdr->len,
+				(unsigned)fa->fa_size);
+		return -1;
+	}
+
+	if ((off_t)hdr->len > entry->size) {
+		LOG_ERR("header len exceeds file size (%u > %ld)", (unsigned)hdr->len, (long)entry->size);
+		return -1;
+	}
+
+	return rc;
+}
+
+static int perform_ota(const struct flash_area *fa, struct fs_file_t *file,
+					   const struct sketch_header_v1 *hdr) {
+	int rc = 0;
+
+	size_t wbs = flash_area_align(fa) > 0 ? flash_area_align(fa) : 1;
+
+	uint8_t chunk[CONFIG_OTA_TRANSCRIPTION_CHUNK_SIZE];
+	__ASSERT(wbs < CONFIG_OTA_TRANSCRIPTION_CHUNK_SIZE,
+			 "OTA internal buffer is smaller(%d) than write block size(%d)",
+			 CONFIG_OTA_TRANSCRIPTION_CHUNK_SIZE, wbs);
+
+	__ASSERT(CONFIG_OTA_TRANSCRIPTION_CHUNK_SIZE % wbs == 0,
+			 "OTA internal buffer(%d) is not multiple of write block "
+			 "size(%d)" CONFIG_OTA_TRANSCRIPTION_CHUNK_SIZE,
+			 wbs);
+
+	off_t offset = 0;
+	size_t remaining = hdr->len;
+	ssize_t n;
+	size_t wlen;
+
+	LOG_INF("erasing flash partition (%u bytes)...", (unsigned)fa->fa_size);
+	rc = flash_area_erase(fa, 0, fa->fa_size);
+
+	if (rc) {
+		LOG_ERR("flash erase failed, rc %d — retry on next boot", rc);
+		goto exit;
+	}
+
+	if ((rc = fs_seek(file, 0, FS_SEEK_SET))) {
+		LOG_ERR("failed to seek to start of file, rc %d — retry on next boot", rc);
+		goto exit;
+	}
+
+	LOG_INF("rewriting sketch binary");
+
+	while (remaining > 0 &&
+		   (n = fs_read(file, chunk, remaining < sizeof(chunk) ? remaining : sizeof(chunk))) > 0) {
+		wlen = (size_t)n;
+		/* Pad the final partial chunk to the write-block-size with 0xFF
+		 * (erased value); flash rejects unaligned writes. */
+		if (wlen % wbs != 0) {
+			memset(chunk + wlen, 0xff, ROUND_UP(wlen, wbs) - wlen);
+			wlen = ROUND_UP(wlen, wbs);
+		}
+
+		if ((rc = flash_area_write(fa, offset, chunk, wlen))) {
+			LOG_ERR("flash write failed at offset %ld, rc %d — retry on next boot", (long)offset,
+					rc);
+
+			goto exit;
+		}
+		offset += n;
+		remaining -= n;
+	}
+
+	if (remaining > 0) {
+		LOG_ERR("short read, %u bytes missing — retry on next boot", (unsigned)remaining);
+		goto exit;
+	}
+
+	LOG_INF("wrote %ld bytes to flash", (long)offset);
+exit:
+	return rc;
+}
+
+/*
+ * Install /ota:/UPDATE.BIN into the sketch partition if present. The sketch
+ * validates the OTA payload (magic, CRC32, decompression) before writing it,
+ * so the loader trusts the file and only re-checks the inner sketch_header_v1.
+ *
+ * On failure before the erase, UPDATE.BIN is removed and the existing sketch
+ * boots. On failure after it, the partition is already partial so UPDATE.BIN
+ * is kept and the next boot retries — the only way back without DFU.
+ */
+int try_ota_update(const struct flash_area *fa) {
+	int rc = 0;
+
+	struct fs_file_t file = {0};
+	struct fs_dirent entry;
+
+	struct sketch_header_v1 *hdr = NULL;
+	char header[SKETCH_HEADER_LEN];
+	bool delete = false;
+
+	LOG_DBG("checking for ota in \"%s\"", CONFIG_OTA_SKETCH_UPDATE_PATH);
+
+	if (fa == NULL) {
+		rc = -1;
+		goto exit;
+	}
+
+	if (fs_stat(CONFIG_OTA_SKETCH_UPDATE_PATH, &entry) != 0) {
+		LOG_DBG("no update pending");
+		goto exit;
+	}
+
+	LOG_INF("update pending, validating...");
+
+	fs_file_t_init(&file);
+	rc = fs_open(&file, CONFIG_OTA_SKETCH_UPDATE_PATH, FS_O_READ);
+	if (rc < 0) {
+		LOG_ERR("failed to open %s, rc %d", CONFIG_OTA_SKETCH_UPDATE_PATH, rc);
+		delete = true;
+		goto exit;
+	}
+
+	if (entry.size < SKETCH_HEADER_LEN) {
+		LOG_ERR("file too small (%ld bytes)", (long)entry.size);
+		delete = true;
+		rc = -1;
+		goto exit;
+	}
+
+	rc = fs_read(&file, header, SKETCH_HEADER_LEN);
+	if (rc != SKETCH_HEADER_LEN) {
+		LOG_ERR("failed to read header");
+		delete = true;
+		rc = -1;
+		goto exit;
+	}
+
+	hdr = (struct sketch_header_v1 *)(header + 7);
+	if ((rc = verify_sketch_header(fa, hdr, &entry))) {
+		delete = true;
+		goto exit;
+	}
+
+	/* Partition becomes inconsistent past here; keep UPDATE.BIN on failure. */
+	LOG_INF("performing ota");
+	if ((rc = perform_ota(fa, &file, hdr))) {
+		goto exit;
+	}
+	delete = true;
+	LOG_INF("update complete");
+exit:
+
+	if (file.mp != NULL && (rc = fs_close(&file))) {
+		LOG_ERR("error on fs_close %d", rc);
+	}
+
+	if (delete && (rc = fs_unlink(CONFIG_OTA_SKETCH_UPDATE_PATH))) {
+		LOG_ERR("error on fs_unlink %d", rc);
+	}
+
+	return rc;
+}
diff --git a/loader/ota/ota_sketch_check.h b/loader/ota/ota_sketch_check.h
new file mode 100644
index 000000000..6b669b314
--- /dev/null
+++ b/loader/ota/ota_sketch_check.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) Arduino s.r.l. and/or its affiliated companies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/storage/flash_map.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// rename this into sketch ota check or something
+// not part of OTA api, internal use
+// TODO remove parameter, the flash area should be provided by config
+int try_ota_update(const struct flash_area *fa);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/platform.txt b/platform.txt
index 4eee89658..bc8821cf4 100644
--- a/platform.txt
+++ b/platform.txt
@@ -69,6 +69,10 @@ build.link_mode=dynamic
 build.boot_mode=wait
 upload.extension=elf-zsk.bin
 
+# OTA generation defaults. Boards opt in by setting build.ota.magic and
+# build.ota.sketch_offset; with magic empty, postobjcopy.3 is a no-op.
+build.ota.magic=
+build.ota.sketch_offset=
 build.ldscript.path={runtime.platform.path}/variants/_ldscripts
 build.link_command="{compiler.path}{compiler.c.elf.cmd}" "-L{build.path}" "-L{build.variant.path}" {compiler.c.elf.flags} {compiler.c.elf.extra_flags} {build.extra_flags} {build.extra_ldflags} {compiler.zephyr.common_ldflags} {compiler.ldflags} {object_files} -Wl,--start-group "{build.path}/{archive_file}" {compiler.zephyr.extra_ldflags} {compiler.libraries.ldflags} -Wl,--end-group {build.link_args.{build.link_mode}}
 
@@ -163,6 +167,7 @@ recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf
 ## Mangle the file
 recipe.hooks.objcopy.postobjcopy.1.pattern="{runtime.tools.zephyr-sketch-tool.path}/zephyr-sketch-tool" {build.zsk_args.debug} {build.zsk_args.mode-{build.link_mode}} {build.zsk_args.startup-mode-{build.boot_mode}} "{build.path}/{build.project_name}.elf"
 recipe.hooks.objcopy.postobjcopy.2.pattern="{runtime.tools.zephyr-sketch-tool.path}/zephyr-sketch-tool" {build.zsk_args.debug} {build.zsk_args.mode-{build.link_mode}} {build.zsk_args.startup-mode-{build.boot_mode}} "{build.path}/{build.project_name}.bin"
+recipe.hooks.objcopy.postobjcopy.3.pattern="{runtime.tools.zephyr-sketch-tool.path}/zephyr-sketch-tool" -ota -ota-loader "{runtime.platform.path}/firmwares/zephyr-{build.variant}.bin" -ota-sketch "{build.path}/{build.project_name}.{upload.extension}" -ota-offset {build.ota.sketch_offset} -ota-magic {build.ota.magic} -output "{build.path}/{build.project_name}"
 
 ## Compute size
 recipe.size.pattern="{runtime.tools.zephyr-check-size.path}/zephyr-check-size" {build.link_mode} "{runtime.platform.path}/firmwares/zephyr-{build.variant}.config" "{build.path}/{build.project_name}.{upload.extension}" "{build.path}/{build.project_name}.elf"
diff --git a/tools/zephyr-sketch-tool/ota.go b/tools/zephyr-sketch-tool/ota.go
index 860a92de7..f1a331bd7 100644
--- a/tools/zephyr-sketch-tool/ota.go
+++ b/tools/zephyr-sketch-tool/ota.go
@@ -78,17 +78,24 @@ func runOTA(loaderPath, sketchPath, offsetStr, magicStr, outputBase string) erro
 		suffix   string
 		payload  []byte
 		compress bool
+		header   bool
 		label    string
 	}{
-		{".ota", sketch, false, "sketch"},
-		{".lzss.ota", sketch, true, "sketch (LZSS)"},
-		{"-bundle.ota", merged, false, "loader+sketch"},
-		{"-bundle.lzss.ota", merged, true, "loader+sketch (LZSS)"},
+		{".ota", sketch, false, true, "sketch"},
+		{".lzss.ota", sketch, true, true, "sketch (LZSS)"},
+		{"-bundle.bin", merged, false, false, "loader+sketch"},
+		{"-bundle.ota", merged, false, true, "loader+sketch"},
+		{"-bundle.lzss.ota", merged, true, true, "loader+sketch (LZSS)"},
 	}
 
 	for _, v := range variants {
 		path := base + v.suffix
-		out := buildOTA(uint32(magic), v.payload, v.compress)
+
+		out := v.payload
+		if v.header {
+			out = buildOTA(uint32(magic), v.payload, v.compress)
+		}
+
 		if err := os.WriteFile(path, out, 0644); err != nil {
 			return fmt.Errorf("write %s: %w", path, err)
 		}
diff --git a/variants/arduino_giga_r1_stm32h747xx_m7/arduino_giga_r1_stm32h747xx_m7.conf b/variants/arduino_giga_r1_stm32h747xx_m7/arduino_giga_r1_stm32h747xx_m7.conf
index bb0db0fd7..5a5bdee72 100644
--- a/variants/arduino_giga_r1_stm32h747xx_m7/arduino_giga_r1_stm32h747xx_m7.conf
+++ b/variants/arduino_giga_r1_stm32h747xx_m7/arduino_giga_r1_stm32h747xx_m7.conf
@@ -212,3 +212,5 @@ CONFIG_NET_CONFIG_AUTO_INIT=n
 CONFIG_NET_CONNECTION_MANAGER=y
 #CONFIG_WIFI_NM_MAX_MANAGED_INTERFACES=2
 CONFIG_NET_L2_ETHERNET_MGMT=y
+
+CONFIG_OTA=y
diff --git a/variants/arduino_nicla_vision_stm32h747xx_m7/arduino_nicla_vision_stm32h747xx_m7.conf b/variants/arduino_nicla_vision_stm32h747xx_m7/arduino_nicla_vision_stm32h747xx_m7.conf
index f6c0395c4..9e3f6191f 100644
--- a/variants/arduino_nicla_vision_stm32h747xx_m7/arduino_nicla_vision_stm32h747xx_m7.conf
+++ b/variants/arduino_nicla_vision_stm32h747xx_m7/arduino_nicla_vision_stm32h747xx_m7.conf
@@ -193,3 +193,5 @@ CONFIG_VIDEO_BUFFER_POOL_ALIGN=32
 CONFIG_VIDEO_GC2145=y
 
 CONFIG_FLASH=y
+
+CONFIG_OTA=y
diff --git a/variants/arduino_opta_stm32h747xx_m7/arduino_opta_stm32h747xx_m7.conf b/variants/arduino_opta_stm32h747xx_m7/arduino_opta_stm32h747xx_m7.conf
index df52fe27c..292ef12b6 100644
--- a/variants/arduino_opta_stm32h747xx_m7/arduino_opta_stm32h747xx_m7.conf
+++ b/variants/arduino_opta_stm32h747xx_m7/arduino_opta_stm32h747xx_m7.conf
@@ -191,3 +191,5 @@ CONFIG_BT_RX_STACK_SIZE=4096
 CONFIG_STM32H7_BOOT_M4_AT_INIT=n
 
 CONFIG_I2C_STM32_V2_TIMING=y
+
+CONFIG_OTA=y
diff --git a/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.conf b/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.conf
index 278b9f9ce..6a2c9f620 100644
--- a/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.conf
+++ b/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.conf
@@ -187,5 +187,7 @@ CONFIG_FS_FATFS_CUSTOM_MOUNT_POINTS="wlan,ota,SD"
 CONFIG_DYNAMIC_INTERRUPTS=n
 
 CONFIG_SPI_ASYNC=y
+CONFIG_LED=y
 
-CONFIG_LED=y
\ No newline at end of file
+CONFIG_OTA=y
+CONFIG_OTA_LOG_LEVEL_DBG=y
diff --git a/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.overlay b/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.overlay
index 122c24ef2..514f66719 100644
--- a/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.overlay
+++ b/variants/arduino_portenta_c33_r7fa6m5bh3cfc/arduino_portenta_c33_r7fa6m5bh3cfc.overlay
@@ -25,13 +25,19 @@
 
 &flash0 {
 	partitions {
+		/delete-node/ partition@10000;
+
 		mcuboot: partition@0 {
 			label = "mcuboot";
 			reg = <0x00000000 DT_SIZE_K(64)>;
 		};
-		code_partition: partition@10000 {
+		sfu_partition: partition@10000 {
+			label = "sfu";
+			reg = <0x00010000 (DT_SIZE_K(128))>;
+		};
+		code_partition: partition@30000 {
 			label = "image-0";
-			reg = <0x00010000 (DT_SIZE_M(1) - DT_SIZE_K(64))>;
+			reg = <0x00030000 (DT_SIZE_M(1) - DT_SIZE_K(64) - DT_SIZE_K(128))>;
 		};
 		user_sketch: partition@100000 {
 			label = "user_sketch";
diff --git a/variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.conf b/variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.conf
index 7d5555dca..0dab568f0 100644
--- a/variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.conf
+++ b/variants/arduino_portenta_h7_stm32h747xx_m7/arduino_portenta_h7_stm32h747xx_m7.conf
@@ -204,3 +204,5 @@ CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
 CONFIG_BT_RX_STACK_SIZE=4096
 
 CONFIG_STM32H7_BOOT_M4_AT_INIT=n
+
+CONFIG_OTA=y