diff --git a/src/network/CMakeLists.txt b/src/network/CMakeLists.txt
index e977400245e..08789d89dec 100644
--- a/src/network/CMakeLists.txt
+++ b/src/network/CMakeLists.txt
@@ -110,6 +110,7 @@ qt_internal_extend_target(Network CONDITION APPLE
 
 qt_internal_extend_target(Network CONDITION WASM
     SOURCES
+        access/qformdatabuilder.cpp access/qformdatabuilder.h
         access/qhttpmultipart.cpp access/qhttpmultipart.h access/qhttpmultipart_p.h
         access/qhttpnetworkheader.cpp access/qhttpnetworkheader_p.h
         access/qnetworkreplywasmimpl.cpp access/qnetworkreplywasmimpl_p.h
@@ -126,6 +127,7 @@ qt_internal_extend_target(Network CONDITION QT_FEATURE_http
         access/http2/huffman.cpp access/http2/huffman_p.h
         access/qabstractprotocolhandler.cpp access/qabstractprotocolhandler_p.h
         access/qdecompresshelper.cpp access/qdecompresshelper_p.h
+        access/qformdatabuilder.cpp access/qformdatabuilder.h
         access/qhttp1configuration.cpp access/qhttp1configuration.h
         access/qhttp2configuration.cpp access/qhttp2configuration.h
         access/qhttp2connection.cpp access/qhttp2connection_p.h
diff --git a/src/network/access/qformdatabuilder.cpp b/src/network/access/qformdatabuilder.cpp
new file mode 100644
index 00000000000..8f467e2c576
--- /dev/null
+++ b/src/network/access/qformdatabuilder.cpp
@@ -0,0 +1,324 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qformdatabuilder.h"
+
+#if QT_CONFIG(mimetype)
+#include "QtCore/qmimedatabase.h"
+#endif
+
+QT_BEGIN_NAMESPACE
+
+/*!
+    \class QFormDataPartBuilder
+    \brief The QFormDataPartBuilder class is a convenience class to simplify
+    the construction of QHttpPart objects.
+    \since 6.8
+
+    \ingroup network
+    \ingroup shared
+    \inmodule QtNetwork
+
+    The QFormDataPartBuilder class can be used to build a QHttpPart object with
+    the content disposition header set to be form-data by default. Then the
+    generated object can be used as part of a multipart message (which is
+    represented by the QHttpMultiPart class).
+
+    \sa QHttpPart, QHttpMultiPart, QFormDataBuilder
+*/
+
+/*!
+    Constructs a QFormDataPartBuilder object and sets \a name as the name
+    parameter of the form-data.
+*/
+QFormDataPartBuilder::QFormDataPartBuilder(QLatin1StringView name, PrivateConstructor /*unused*/)
+{
+    static_assert(std::is_nothrow_move_constructible_v<decltype(m_body)>);
+    static_assert(std::is_nothrow_move_assignable_v<decltype(m_body)>);
+
+    m_headerValue += "form-data; name=\"";
+    for (auto c : name) {
+        if (c == '"' || c == '\\')
+            m_headerValue += '\\';
+        m_headerValue += c;
+    }
+    m_headerValue += "\"";
+}
+
+/*!
+    \fn QFormDataPartBuilder::QFormDataPartBuilder(QFormDataPartBuilder &&other) noexcept
+
+    Move-constructs a QFormDataPartBuilder instance, making it point at the same
+    object that \a other was pointing to.
+*/
+
+/*!
+    \fn QFormDataPartBuilder &QFormDataPartBuilder::operator=(QFormDataPartBuilder &&other)
+
+    Move-assigns \a other to this QFormDataPartBuilder instance.
+*/
+
+/*!
+    Destroys the QFormDataPartBuilder object.
+*/
+
+QFormDataPartBuilder::~QFormDataPartBuilder()
+    = default;
+
+static QByteArray buildFileName(QLatin1StringView view)
+{
+    QByteArray fileName;
+    fileName += "; filename";
+    QByteArrayView encoding = "=";
+
+    for (uchar c : view) {
+        if (c > 127) {
+            encoding = "*=ISO-8859-1''";
+            break;
+        }
+    }
+
+    fileName += encoding;
+    fileName += QByteArray::fromRawData(view.data(), view.size()).toPercentEncoding();
+    return fileName;
+}
+
+static QByteArray buildFileName(QUtf8StringView view)
+{
+    QByteArrayView bv = view;
+    QByteArray fileName;
+    fileName += "; filename";
+    QByteArrayView encoding = "=";
+
+    for (uchar c : bv) {
+        if (c > 127) {
+            encoding = "*=UTF-8''";
+            break;
+        }
+    }
+
+    fileName += encoding;
+    fileName += QByteArray::fromRawData(bv.data(), bv.size()).toPercentEncoding();
+    return fileName;
+}
+
+static QByteArray buildFileName(QStringView view)
+{
+    QByteArray fileName;
+    fileName += "; filename";
+    QByteArrayView encoding = "=";
+    bool needsUtf8 = false;
+
+    for (QChar c : view) {
+        if (c > u'\xff') {
+            encoding = "*=UTF-8''";
+            needsUtf8 = true;
+            break;
+        } else if (c > u'\x7f') {
+            encoding = "*=ISO-8859-1''";
+        }
+    }
+
+    fileName += encoding;
+
+    if (needsUtf8)
+        fileName += view.toUtf8().toPercentEncoding();
+    else
+        fileName += view.toLatin1().toPercentEncoding();
+
+    return fileName;
+}
+
+QFormDataPartBuilder &QFormDataPartBuilder::setBodyHelper(const QByteArray &data,
+                                                          QAnyStringView fileName)
+{
+    if (fileName.isEmpty())
+        m_bodyName = QByteArray();
+    else
+        m_bodyName = fileName.visit([&](auto name) { return buildFileName(name); });
+
+    m_originalBodyName = fileName.toString();
+    m_body = data;
+    return *this;
+}
+
+/*!
+    Sets \a data as the body of this MIME part and, if given, \a fileName as the
+    file name parameter in the content disposition header.
+
+    A subsequent call to setBodyDevice() discards the body and the device will
+    be used instead.
+
+    For a large amount of data (e.g. an image), setBodyDevice() is preferred,
+    which will not copy the data internally.
+
+    \sa setBodyDevice()
+*/
+
+QFormDataPartBuilder &QFormDataPartBuilder::setBody(QByteArrayView data,
+                                                    QAnyStringView fileName)
+{
+    return setBody(data.toByteArray(), fileName);
+}
+
+/*!
+    Sets \a body as the body device of this part and \a fileName as the file
+    name parameter in the content disposition header.
+
+    A subsequent call to setBody() discards the body device and the data set by
+    setBody() will be used instead.
+
+    For large amounts of data this method should be preferred over setBody(),
+    because the content is not copied when using this method, but read
+    directly from the device.
+
+    \a body must be open and readable. QFormDataPartBuilder does not take
+    ownership of \a body, i.e. the device must be closed and destroyed if
+    necessary.
+
+    \sa setBody(), QHttpPart::setBodyDevice()
+  */
+
+QFormDataPartBuilder &QFormDataPartBuilder::setBodyDevice(QIODevice *body, QAnyStringView fileName)
+{
+    if (fileName.isEmpty())
+        m_bodyName = QByteArray();
+    else
+        m_bodyName = fileName.visit([&](auto name) { return buildFileName(name); });
+
+    m_originalBodyName = fileName.toString();
+    m_body = body;
+    return *this;
+}
+
+/*!
+    Sets the headers specified in \a headers.
+
+    \note The "content-type" and "content-disposition" headers, if any are
+    specified in \a headers, will be overwritten by the class.
+*/
+
+QFormDataPartBuilder &QFormDataPartBuilder::setHeaders(const QHttpHeaders &headers)
+{
+    m_httpHeaders = headers;
+    return *this;
+}
+
+/*!
+    Generates a QHttpPart and sets the content disposition header as form-data.
+
+    When this function called, it uses the MIME database to deduce the type the
+    body based on its name and then sets the deduced type as the content type
+    header.
+*/
+
+QHttpPart QFormDataPartBuilder::build()
+{
+    QHttpPart httpPart;
+
+    if (!m_bodyName.isEmpty())
+        m_headerValue += m_bodyName;     // RFC 5987 Section 3.2.1
+
+#if QT_CONFIG(mimetype)
+    QMimeDatabase db;
+    QMimeType mimeType = std::visit([&](auto &arg) {
+        return db.mimeTypeForFileNameAndData(m_originalBodyName, arg);
+    }, m_body);
+#endif
+    for (qsizetype i = 0; i < m_httpHeaders.size(); i++) {
+        httpPart.setRawHeader(QByteArrayView(m_httpHeaders.nameAt(i)).toByteArray(),
+                                             m_httpHeaders.valueAt(i).toByteArray());
+    }
+#if QT_CONFIG(mimetype)
+    httpPart.setHeader(QNetworkRequest::ContentTypeHeader, mimeType.name());
+#endif
+    httpPart.setHeader(QNetworkRequest::ContentDispositionHeader, m_headerValue);
+
+
+    if (auto d = std::get_if<QIODevice*>(&m_body))
+        httpPart.setBodyDevice(*d);
+    else if (auto b = std::get_if<QByteArray>(&m_body))
+        httpPart.setBody(*b);
+    else
+        Q_UNREACHABLE();
+
+    return httpPart;
+}
+
+/*!
+    \class QFormDataBuilder
+    \brief The QFormDataBuilder class is a convenience class to simplify
+    the construction of QHttpMultiPart objects.
+    \since 6.8
+
+    \ingroup network
+    \ingroup shared
+    \inmodule QtNetwork
+
+    The QFormDataBuilder class can be used to build a QHttpMultiPart object
+    with the content type set to be FormDataType by default.
+
+    \sa QHttpPart, QHttpMultiPart, QFormDataPartBuilder
+*/
+
+/*!
+    Constructs an empty QFormDataBuilder object.
+*/
+
+QFormDataBuilder::QFormDataBuilder()
+    = default;
+
+/*!
+    Destroys the QFormDataBuilder object.
+*/
+
+QFormDataBuilder::~QFormDataBuilder()
+    = default;
+
+/*!
+    \fn QFormDataBuilder::QFormDataBuilder(QFormDataBuilder &&other) noexcept
+
+    Move-constructs a QFormDataBuilder instance, making it point at the same
+    object that \a other was pointing to.
+*/
+
+/*!
+    \fn QFormDataBuilder &QFormDataBuilder::operator=(QFormDataBuilder &&other) noexcept
+
+    Move-assigns \a other to this QFormDataBuilder instance.
+*/
+
+/*!
+    Constructs and returns a reference to a QFormDataPartBuilder object and sets
+    \a name as the name parameter of the form-data. The returned reference is
+    valid until the next call to this function.
+
+    \sa QFormDataPartBuilder, QHttpPart
+*/
+
+QFormDataPartBuilder &QFormDataBuilder::part(QLatin1StringView name)
+{
+    static_assert(std::is_nothrow_move_constructible_v<decltype(m_parts)>);
+    static_assert(std::is_nothrow_move_assignable_v<decltype(m_parts)>);
+
+    return m_parts.emplace_back(name, QFormDataPartBuilder::PrivateConstructor());
+}
+
+/*!
+    Constructs and returns a pointer to a QHttpMultipart object. The caller
+    takes ownership of the generated QHttpMultiPart object.
+
+    \sa QHttpMultiPart
+*/
+
+std::unique_ptr<QHttpMultiPart> QFormDataBuilder::buildMultiPart()
+{
+    auto multiPart = std::make_unique<QHttpMultiPart>(QHttpMultiPart::FormDataType);
+
+    for (auto &part : m_parts)
+        multiPart->append(part.build());
+
+    return multiPart;
+}
+
+QT_END_NAMESPACE
diff --git a/src/network/access/qformdatabuilder.h b/src/network/access/qformdatabuilder.h
new file mode 100644
index 00000000000..1bbf9066cd7
--- /dev/null
+++ b/src/network/access/qformdatabuilder.h
@@ -0,0 +1,124 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QFORMDATABUILDER_H
+#define QFORMDATABUILDER_H
+
+#include <QtNetwork/qtnetworkglobal.h>
+#include <QtNetwork/qhttpheaders.h>
+#include <QtNetwork/qhttpmultipart.h>
+
+#include <QtCore/qbytearray.h>
+#include <QtCore/qiodevice.h>
+#include <QtCore/qstring.h>
+
+#include <memory>
+#include <variant>
+#include <vector>
+
+#ifndef Q_OS_WASM
+QT_REQUIRE_CONFIG(http);
+#endif
+
+class tst_QFormDataBuilder;
+
+QT_BEGIN_NAMESPACE
+
+class QHttpPartPrivate;
+class QHttpMultiPart;
+class QDebug;
+
+class QFormDataPartBuilder
+{
+    struct PrivateConstructor { explicit PrivateConstructor() = default; };
+public:
+    Q_NETWORK_EXPORT explicit QFormDataPartBuilder(QLatin1StringView name, PrivateConstructor);
+
+    QFormDataPartBuilder(QFormDataPartBuilder &&other) noexcept
+        : m_headerValue(std::move(other.m_headerValue)),
+          m_bodyName(std::move(other.m_bodyName)),
+          m_originalBodyName(std::move(other.m_originalBodyName)),
+          m_httpHeaders(std::move(other.m_httpHeaders)),
+          m_body(std::move(other.m_body)),
+          m_reserved(std::exchange(other.m_reserved, nullptr))
+    {
+
+    }
+
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QFormDataPartBuilder)
+    void swap(QFormDataPartBuilder &other) noexcept
+    {
+        m_headerValue.swap(other.m_headerValue);
+        m_bodyName.swap(other.m_bodyName);
+        m_originalBodyName.swap(other.m_originalBodyName);
+        m_httpHeaders.swap(other.m_httpHeaders);
+        m_body.swap(other.m_body);
+        qt_ptr_swap(m_reserved, other.m_reserved);
+    }
+
+    Q_NETWORK_EXPORT ~QFormDataPartBuilder();
+
+    Q_WEAK_OVERLOAD QFormDataPartBuilder &setBody(const QByteArray &data,
+                                                  QAnyStringView fileName = {})
+    { return setBodyHelper(data, fileName); }
+
+    Q_NETWORK_EXPORT QFormDataPartBuilder &setBody(QByteArrayView data,
+                                                   QAnyStringView fileName = {});
+    Q_NETWORK_EXPORT QFormDataPartBuilder &setBodyDevice(QIODevice *body,
+                                                         QAnyStringView fileName = {});
+    Q_NETWORK_EXPORT QFormDataPartBuilder &setHeaders(const QHttpHeaders &headers);
+private:
+    Q_DISABLE_COPY(QFormDataPartBuilder)
+
+    Q_NETWORK_EXPORT QFormDataPartBuilder &setBodyHelper(const QByteArray &data,
+                                                         QAnyStringView fileName = {});
+    Q_NETWORK_EXPORT QHttpPart build();
+
+    QByteArray m_headerValue;
+    QByteArray m_bodyName;
+    QString m_originalBodyName;
+    QHttpHeaders m_httpHeaders;
+    std::variant<QIODevice*, QByteArray> m_body;
+    void *m_reserved = nullptr;
+
+    friend class QFormDataBuilder;
+    friend class ::tst_QFormDataBuilder;
+    friend void swap(QFormDataPartBuilder &lhs, QFormDataPartBuilder &rhs) noexcept
+    { lhs.swap(rhs); }
+};
+
+class QFormDataBuilder
+{
+public:
+    Q_NETWORK_EXPORT explicit QFormDataBuilder();
+
+    QFormDataBuilder(QFormDataBuilder &&other) noexcept
+        : m_parts(std::move(other.m_parts)),
+          m_reserved(std::exchange(other.m_reserved, nullptr))
+    {
+
+    }
+
+    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QFormDataBuilder)
+    void swap(QFormDataBuilder &other) noexcept
+    {
+        m_parts.swap(other.m_parts);
+        qt_ptr_swap(m_reserved, other.m_reserved);
+    }
+
+    Q_NETWORK_EXPORT ~QFormDataBuilder();
+    Q_NETWORK_EXPORT QFormDataPartBuilder &part(QLatin1StringView name);
+    Q_NETWORK_EXPORT std::unique_ptr<QHttpMultiPart> buildMultiPart();
+private:
+    std::vector<QFormDataPartBuilder> m_parts;
+    void *m_reserved = nullptr;
+
+    friend void swap(QFormDataBuilder &lhs, QFormDataBuilder &rhs) noexcept
+    { lhs.swap(rhs); }
+
+    Q_DISABLE_COPY(QFormDataBuilder)
+};
+
+QT_END_NAMESPACE
+
+#endif // QFORMDATABUILDER_H
diff --git a/tests/auto/network/access/CMakeLists.txt b/tests/auto/network/access/CMakeLists.txt
index d1130f832e7..ed99aa87460 100644
--- a/tests/auto/network/access/CMakeLists.txt
+++ b/tests/auto/network/access/CMakeLists.txt
@@ -14,6 +14,7 @@ add_subdirectory(qnetworkcachemetadata)
 add_subdirectory(qabstractnetworkcache)
 if(QT_FEATURE_http)
     add_subdirectory(qnetworkreply_local)
+    add_subdirectory(qformdatabuilder)
     add_subdirectory(qnetworkrequestfactory)
     add_subdirectory(qrestaccessmanager)
 endif()
diff --git a/tests/auto/network/access/qformdatabuilder/CMakeLists.txt b/tests/auto/network/access/qformdatabuilder/CMakeLists.txt
new file mode 100644
index 00000000000..dde2dc10e0c
--- /dev/null
+++ b/tests/auto/network/access/qformdatabuilder/CMakeLists.txt
@@ -0,0 +1,22 @@
+# Copyright (C) 2024 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+if(NOT QT_BUILD_STANDALONE_TESTS AND NOT QT_BUILDING_QT)
+    cmake_minimum_required(VERSION 3.16)
+    project(tst_qformdatabuilder LANGUAGES CXX)
+    find_package(Qt6BuildInternals REQUIRED COMPONENTS STANDALONE_TEST)
+endif()
+
+qt_internal_add_test(tst_qformdatabuilder
+    SOURCES
+        tst_qformdatabuilder.cpp
+    LIBRARIES
+        Qt::Core
+        Qt::Network
+    TESTDATA
+        rfc3252.txt
+        image1.jpg
+        document.docx
+        sheet.xlsx
+)
+
diff --git a/tests/auto/network/access/qformdatabuilder/document.docx b/tests/auto/network/access/qformdatabuilder/document.docx
new file mode 100644
index 00000000000..49005f14b6d
Binary files /dev/null and b/tests/auto/network/access/qformdatabuilder/document.docx differ
diff --git a/tests/auto/network/access/qformdatabuilder/image1.jpg b/tests/auto/network/access/qformdatabuilder/image1.jpg
new file mode 100644
index 00000000000..d1d27bf7cfa
Binary files /dev/null and b/tests/auto/network/access/qformdatabuilder/image1.jpg differ
diff --git a/tests/auto/network/access/qformdatabuilder/rfc3252.txt b/tests/auto/network/access/qformdatabuilder/rfc3252.txt
new file mode 100644
index 00000000000..5436ce5b26d
--- /dev/null
+++ b/tests/auto/network/access/qformdatabuilder/rfc3252.txt
@@ -0,0 +1 @@
+some text for reference
diff --git a/tests/auto/network/access/qformdatabuilder/sheet.xlsx b/tests/auto/network/access/qformdatabuilder/sheet.xlsx
new file mode 100644
index 00000000000..2cb1ec73611
Binary files /dev/null and b/tests/auto/network/access/qformdatabuilder/sheet.xlsx differ
diff --git a/tests/auto/network/access/qformdatabuilder/tst_qformdatabuilder.cpp b/tests/auto/network/access/qformdatabuilder/tst_qformdatabuilder.cpp
new file mode 100644
index 00000000000..70d9b4b1bdc
--- /dev/null
+++ b/tests/auto/network/access/qformdatabuilder/tst_qformdatabuilder.cpp
@@ -0,0 +1,204 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include <QtNetwork/qformdatabuilder.h>
+
+#include <QtCore/qbuffer.h>
+#include <QtCore/qfile.h>
+
+#include <QtTest/qtest.h>
+
+using namespace Qt::StringLiterals;
+
+class tst_QFormDataBuilder : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void generateQHttpPartWithDevice_data();
+    void generateQHttpPartWithDevice();
+
+    void escapesBackslashAndQuotesInFilenameAndName_data();
+    void escapesBackslashAndQuotesInFilenameAndName();
+
+    void picksUtf8EncodingOnlyIfL1OrAsciiDontSuffice_data();
+    void picksUtf8EncodingOnlyIfL1OrAsciiDontSuffice();
+};
+
+void tst_QFormDataBuilder::generateQHttpPartWithDevice_data()
+{
+    QTest::addColumn<QLatin1StringView>("name_data");
+    QTest::addColumn<QString>("real_file_name");
+    QTest::addColumn<QString>("body_name_data");
+    QTest::addColumn<QByteArray>("expected_content_type_data");
+    QTest::addColumn<QByteArray>("expected_content_disposition_data");
+
+    QTest::newRow("txt-ascii") << "text"_L1 << "rfc3252.txt" << "rfc3252.txt" << "text/plain"_ba
+                               << "form-data; name=\"text\"; filename=rfc3252.txt"_ba;
+    QTest::newRow("txt-latin") << "text"_L1 << "rfc3252.txt" << "szöveg.txt" << "text/plain"_ba
+                               << "form-data; name=\"text\"; filename*=ISO-8859-1''sz%F6veg.txt"_ba;
+    QTest::newRow("txt-unicode") << "text"_L1 << "rfc3252.txt" << "テキスト.txt" << "text/plain"_ba
+                                 << "form-data; name=\"text\"; filename*=UTF-8''%E3%83%86%E3%82%AD%E3%82%B9%E3%83%88.txt"_ba;
+
+    QTest::newRow("jpg-ascii") << "image"_L1 << "image1.jpg" << "image1.jpg" << "image/jpeg"_ba
+                               << "form-data; name=\"image\"; filename=image1.jpg"_ba;
+    QTest::newRow("jpg-latin") << "image"_L1 << "image1.jpg" << "kép.jpg" << "image/jpeg"_ba
+                               << "form-data; name=\"image\"; filename*=ISO-8859-1''k%E9p.jpg"_ba;
+    QTest::newRow("jpg-unicode") << "image"_L1 << "image1.jpg" << "絵.jpg" << "image/jpeg"_ba
+                                 << "form-data; name=\"image\"; filename*=UTF-8''%E7%B5%B5"_ba;
+
+    QTest::newRow("doc-ascii") << "text"_L1 << "document.docx" << "word.docx"
+                               << "application/vnd.openxmlformats-officedocument.wordprocessingml.document"_ba
+                               << "form-data; name=\"text\"; filename=word.docx"_ba;
+    QTest::newRow("doc-latin") << "text"_L1 << "document.docx" << "szöveg.docx"
+                               << "application/vnd.openxmlformats-officedocument.wordprocessingml.document"_ba
+                               << "form-data; name=\"text\"; filename*=ISO-8859-1''sz%F6veg.docx"_ba;
+    QTest::newRow("doc-unicode") << "text"_L1 << "document.docx" << "テキスト.docx"
+                                 << "application/vnd.openxmlformats-officedocument.wordprocessingml.document"_ba
+                                 << "form-data; name=\"text\"; filename*=UTF-8''%E3%83%86%E3%82%AD%E3%82%B9%E3%83%88.docx"_ba;
+
+    QTest::newRow("xls-ascii") << "spreadsheet"_L1 << "sheet.xlsx" << "sheet.xlsx"
+                               << "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"_ba
+                               << "form-data; name=\"spreadsheet\"; filename=sheet.xlsx"_ba;
+    QTest::newRow("xls-latin") << "spreadsheet"_L1 << "sheet.xlsx" << "szöveg.xlsx"
+                               << "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"_ba
+                               << "form-data; name=\"spreadsheet\"; filename*=ISO-8859-1''sz%F6veg.xlsx"_ba;
+    QTest::newRow("xls-unicode") << "spreadsheet"_L1 << "sheet.xlsx" << "テキスト.xlsx"
+                                 << "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"_ba
+                                 << "form-data; name=\"spreadsheet\"; filename*=UTF-8''%E3%83%86%E3%82%AD%E3%82%B9%E3%83%88.xlsx"_ba;
+
+}
+
+void tst_QFormDataBuilder::generateQHttpPartWithDevice()
+{
+    QFETCH(const QLatin1StringView, name_data);
+    QFETCH(const QString, real_file_name);
+    QFETCH(const QString, body_name_data);
+    QFETCH(const QByteArray, expected_content_type_data);
+    QFETCH(const QByteArray, expected_content_disposition_data);
+
+    QString testData = QFileInfo(QFINDTESTDATA(real_file_name)).absoluteFilePath();
+    QFile data_file(testData);
+
+    QHttpPart httpPart = QFormDataPartBuilder(name_data, QFormDataPartBuilder::PrivateConstructor())
+                        .setBodyDevice(&data_file, body_name_data)
+                        .build();
+
+    QByteArray msg;
+    {
+        QBuffer buf(&msg);
+        QVERIFY(buf.open(QIODevice::WriteOnly));
+        QDebug debug(&buf);
+        debug << httpPart;
+    }
+
+    QVERIFY(msg.contains(expected_content_type_data));
+    QVERIFY(msg.contains(expected_content_disposition_data));
+}
+
+void tst_QFormDataBuilder::escapesBackslashAndQuotesInFilenameAndName_data()
+{
+    QTest::addColumn<QLatin1StringView>("name_data");
+    QTest::addColumn<QString>("body_name_data");
+    QTest::addColumn<QByteArray>("expected_content_type_data");
+    QTest::addColumn<QByteArray>("expected_content_disposition_data");
+
+    QTest::newRow("quote") << "t\"ext"_L1 << "rfc3252.txt" << "text/plain"_ba
+                           << R"(form-data; name="t\"ext"; filename=rfc3252.txt)"_ba;
+
+    QTest::newRow("slash") << "t\\ext"_L1 << "rfc3252.txt" << "text/plain"_ba
+                           << R"(form-data; name="t\\ext"; filename=rfc3252.txt)"_ba;
+
+    QTest::newRow("quotes") << "t\"e\"xt"_L1 << "rfc3252.txt" << "text/plain"_ba
+                            << R"(form-data; name="t\"e\"xt"; filename=rfc3252.txt)"_ba;
+
+    QTest::newRow("slashes") << "t\\\\ext"_L1 << "rfc3252.txt" << "text/plain"_ba
+                             << R"(form-data; name="t\\\\ext"; filename=rfc3252.txt)"_ba;
+
+    QTest::newRow("quote-slash") << "t\"ex\\t"_L1 << "rfc3252.txt" << "text/plain"_ba
+                                 << R"(form-data; name="t\"ex\\t"; filename=rfc3252.txt)"_ba;
+
+    QTest::newRow("quotes-slashes") << "t\"e\"x\\t\\"_L1 << "rfc3252.txt" << "text/plain"_ba
+                                    << R"(form-data; name="t\"e\"x\\t\\"; filename=rfc3252.txt)"_ba;
+}
+
+void tst_QFormDataBuilder::escapesBackslashAndQuotesInFilenameAndName()
+{
+    QFETCH(const QLatin1StringView, name_data);
+    QFETCH(const QString, body_name_data);
+    QFETCH(const QByteArray, expected_content_type_data);
+    QFETCH(const QByteArray, expected_content_disposition_data);
+
+    QFile dummy_file(body_name_data);
+
+    QHttpPart httpPart = QFormDataPartBuilder(name_data, QFormDataPartBuilder::PrivateConstructor())
+                        .setBodyDevice(&dummy_file, body_name_data)
+                        .build();
+
+    QByteArray msg;
+    {
+        QBuffer buf(&msg);
+        QVERIFY(buf.open(QIODevice::WriteOnly));
+        QDebug debug(&buf);
+        debug << httpPart;
+    }
+
+    QVERIFY(msg.contains(expected_content_type_data));
+    QVERIFY(msg.contains(expected_content_disposition_data));
+}
+
+void tst_QFormDataBuilder::picksUtf8EncodingOnlyIfL1OrAsciiDontSuffice_data()
+{
+    QTest::addColumn<QLatin1StringView>("name_data");
+    QTest::addColumn<QAnyStringView>("body_name_data");
+    QTest::addColumn<QByteArray>("expected_content_type_data");
+    QTest::addColumn<QByteArray>("expected_content_disposition_data");
+
+    QTest::newRow("latin1-ascii") << "text"_L1 << QAnyStringView("rfc3252.txt"_L1) << "text/plain"_ba
+                                  << "form-data; name=\"text\"; filename=rfc3252.txt"_ba;
+    QTest::newRow("u8-ascii") << "text"_L1 << QAnyStringView(u8"rfc3252.txt") << "text/plain"_ba
+                              << "form-data; name=\"text\"; filename=rfc3252.txt"_ba;
+    QTest::newRow("u-ascii") << "text"_L1 << QAnyStringView(u"rfc3252.txt") << "text/plain"_ba
+                             << "form-data; name=\"text\"; filename=rfc3252.txt"_ba;
+
+
+    QTest::newRow("latin1-latin") << "text"_L1 << QAnyStringView("sz\366veg.txt"_L1) << "text/plain"_ba
+                                  << "form-data; name=\"text\"; filename*=ISO-8859-1''sz%F6veg.txt"_ba;
+    QTest::newRow("u8-latin") << "text"_L1 << QAnyStringView(u8"szöveg.txt") << "text/plain"_ba
+                              << "form-data; name=\"text\"; filename*=ISO-8859-1''sz%F6veg.txt"_ba;
+    QTest::newRow("u-latin") << "text"_L1 << QAnyStringView(u"szöveg.txt") << "text/plain"_ba
+                             << "form-data; name=\"text\"; filename*=ISO-8859-1''sz%F6veg.txt"_ba;
+
+    QTest::newRow("u8-u8") << "text"_L1 << QAnyStringView(u8"テキスト.txt") << "text/plain"_ba
+                           << "form-data; name=\"text\"; filename*=UTF-8''%E3%83%86%E3%82%AD%E3%82%B9%E3%83%88.txt"_ba;
+}
+
+void tst_QFormDataBuilder::picksUtf8EncodingOnlyIfL1OrAsciiDontSuffice()
+{
+    QFETCH(const QLatin1StringView, name_data);
+    QFETCH(const QAnyStringView, body_name_data);
+    QFETCH(const QByteArray, expected_content_type_data);
+    QFETCH(const QByteArray, expected_content_disposition_data);
+
+    QBuffer buff;
+
+    QHttpPart httpPart = QFormDataPartBuilder(name_data, QFormDataPartBuilder::PrivateConstructor())
+                        .setBodyDevice(&buff, body_name_data)
+                        .build();
+
+    QByteArray msg;
+    {
+        QBuffer buf(&msg);
+        QVERIFY(buf.open(QIODevice::WriteOnly));
+        QDebug debug(&buf);
+        debug << httpPart;
+    }
+
+    QVERIFY(msg.contains(expected_content_type_data));
+    QEXPECT_FAIL("u8-latin", "will be fixed in subsequent patch", Continue);
+    QVERIFY(msg.contains(expected_content_disposition_data));
+}
+
+
+QTEST_MAIN(tst_QFormDataBuilder)
+#include "tst_qformdatabuilder.moc"