diff --git a/esphome/components/web_server_idf/multipart_parser_utils.cpp b/esphome/components/web_server_idf/multipart_parser_utils.cpp
new file mode 100644
index 0000000000..1d85b3b661
--- /dev/null
+++ b/esphome/components/web_server_idf/multipart_parser_utils.cpp
@@ -0,0 +1,209 @@
+#include "esphome/core/defines.h"
+#ifdef USE_ESP_IDF
+#ifdef USE_WEBSERVER_OTA
+#include "multipart_parser_utils.h"
+
+namespace esphome {
+namespace web_server_idf {
+
+// Helper function for case-insensitive string region comparison
+bool str_ncmp_ci(const char *s1, const char *s2, size_t n) {
+  for (size_t i = 0; i < n; i++) {
+    if (!char_equals_ci(s1[i], s2[i])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+// Case-insensitive string prefix check
+bool str_startswith_case_insensitive(const std::string &str, const std::string &prefix) {
+  if (str.length() < prefix.length()) {
+    return false;
+  }
+  return str_ncmp_ci(str.c_str(), prefix.c_str(), prefix.length());
+}
+
+// Find a substring case-insensitively
+size_t str_find_case_insensitive(const std::string &haystack, const std::string &needle, size_t pos) {
+  if (needle.empty() || pos >= haystack.length()) {
+    return std::string::npos;
+  }
+
+  const size_t needle_len = needle.length();
+  const size_t max_pos = haystack.length() - needle_len;
+
+  for (size_t i = pos; i <= max_pos; i++) {
+    if (str_ncmp_ci(haystack.c_str() + i, needle.c_str(), needle_len)) {
+      return i;
+    }
+  }
+
+  return std::string::npos;
+}
+
+// Extract a parameter value from a header line
+// Handles both quoted and unquoted values
+std::string extract_header_param(const std::string &header, const std::string &param) {
+  size_t search_pos = 0;
+
+  while (search_pos < header.length()) {
+    // Look for param name
+    size_t pos = str_find_case_insensitive(header, param, search_pos);
+    if (pos == std::string::npos) {
+      return "";
+    }
+
+    // Check if this is a word boundary (not part of another parameter)
+    if (pos > 0 && header[pos - 1] != ' ' && header[pos - 1] != ';' && header[pos - 1] != '\t') {
+      search_pos = pos + 1;
+      continue;
+    }
+
+    // Move past param name
+    pos += param.length();
+
+    // Skip whitespace and find '='
+    while (pos < header.length() && (header[pos] == ' ' || header[pos] == '\t')) {
+      pos++;
+    }
+
+    if (pos >= header.length() || header[pos] != '=') {
+      search_pos = pos;
+      continue;
+    }
+
+    pos++;  // Skip '='
+
+    // Skip whitespace after '='
+    while (pos < header.length() && (header[pos] == ' ' || header[pos] == '\t')) {
+      pos++;
+    }
+
+    if (pos >= header.length()) {
+      return "";
+    }
+
+    // Check if value is quoted
+    if (header[pos] == '"') {
+      pos++;
+      size_t end = header.find('"', pos);
+      if (end != std::string::npos) {
+        return header.substr(pos, end - pos);
+      }
+      // Malformed - no closing quote
+      return "";
+    }
+
+    // Unquoted value - find the end (semicolon, comma, or end of string)
+    size_t end = pos;
+    while (end < header.length() && header[end] != ';' && header[end] != ',' && header[end] != ' ' &&
+           header[end] != '\t') {
+      end++;
+    }
+
+    return header.substr(pos, end - pos);
+  }
+
+  return "";
+}
+
+// Case-insensitive string search (like strstr but case-insensitive)
+const char *stristr(const char *haystack, const char *needle) {
+  if (!haystack || !needle) {
+    return nullptr;
+  }
+
+  size_t needle_len = strlen(needle);
+  if (needle_len == 0) {
+    return haystack;
+  }
+
+  for (const char *p = haystack; *p; p++) {
+    if (str_ncmp_ci(p, needle, needle_len)) {
+      return p;
+    }
+  }
+
+  return nullptr;
+}
+
+// Parse boundary from Content-Type header
+// Returns true if boundary found, false otherwise
+// boundary_start and boundary_len will point to the boundary value
+bool parse_multipart_boundary(const char *content_type, const char **boundary_start, size_t *boundary_len) {
+  if (!content_type) {
+    return false;
+  }
+
+  // Check for multipart/form-data (case-insensitive)
+  if (!stristr(content_type, "multipart/form-data")) {
+    return false;
+  }
+
+  // Look for boundary parameter
+  const char *b = stristr(content_type, "boundary=");
+  if (!b) {
+    return false;
+  }
+
+  const char *start = b + 9;  // Skip "boundary="
+
+  // Skip whitespace
+  while (*start == ' ' || *start == '\t') {
+    start++;
+  }
+
+  if (!*start) {
+    return false;
+  }
+
+  // Find end of boundary
+  const char *end = start;
+  if (*end == '"') {
+    // Quoted boundary
+    start++;
+    end++;
+    while (*end && *end != '"') {
+      end++;
+    }
+    *boundary_len = end - start;
+  } else {
+    // Unquoted boundary
+    while (*end && *end != ' ' && *end != ';' && *end != '\r' && *end != '\n' && *end != '\t') {
+      end++;
+    }
+    *boundary_len = end - start;
+  }
+
+  if (*boundary_len == 0) {
+    return false;
+  }
+
+  *boundary_start = start;
+  return true;
+}
+
+// Check if content type is form-urlencoded (case-insensitive)
+bool is_form_urlencoded(const char *content_type) {
+  if (!content_type) {
+    return false;
+  }
+
+  return stristr(content_type, "application/x-www-form-urlencoded") != nullptr;
+}
+
+// Trim whitespace from both ends of a string
+std::string str_trim(const std::string &str) {
+  size_t start = str.find_first_not_of(" \t\r\n");
+  if (start == std::string::npos) {
+    return "";
+  }
+  size_t end = str.find_last_not_of(" \t\r\n");
+  return str.substr(start, end - start + 1);
+}
+
+}  // namespace web_server_idf
+}  // namespace esphome
+#endif  // USE_WEBSERVER_OTA
+#endif  // USE_ESP_IDF
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