diff --git a/core/fpdfapi/parser/cpdf_flateencoder.cpp b/core/fpdfapi/parser/cpdf_flateencoder.cpp
index 64acd72..8d6d052 100644
--- a/core/fpdfapi/parser/cpdf_flateencoder.cpp
+++ b/core/fpdfapi/parser/cpdf_flateencoder.cpp
@@ -13,6 +13,7 @@
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fpdfapi/parser/cpdf_stream_acc.h"
 #include "core/fpdfapi/parser/fpdf_parser_decode.h"
+#include "core/fxcodec/flate/flatemodule.h"
 #include "third_party/base/check.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
@@ -40,7 +41,7 @@
   }
 
   // TODO(thestig): Move to Init() and check for empty return value?
-  m_Data = ::FlateEncode(m_pAcc->GetSpan());
+  m_Data = FlateModule::Encode(m_pAcc->GetSpan());
   m_pClonedDict = ToDictionary(pStream->GetDict()->Clone());
   m_pClonedDict->SetNewFor<CPDF_Number>(
       "Length", pdfium::base::checked_cast<int>(GetSpan().size()));
diff --git a/core/fpdfapi/parser/fpdf_parser_decode.cpp b/core/fpdfapi/parser/fpdf_parser_decode.cpp
index 29b2eb6..3f7d08c 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode.cpp
+++ b/core/fpdfapi/parser/fpdf_parser_decode.cpp
@@ -604,14 +604,3 @@
   result += '>';
   return result;
 }
-
-DataVector<uint8_t> FlateEncode(pdfium::span<const uint8_t> src_span) {
-  return FlateModule::Encode(src_span);
-}
-
-uint32_t FlateDecode(pdfium::span<const uint8_t> src_span,
-                     std::unique_ptr<uint8_t, FxFreeDeleter>* dest_buf,
-                     uint32_t* dest_size) {
-  return FlateModule::FlateOrLZWDecode(false, src_span, false, 0, 0, 0, 0, 0,
-                                       dest_buf, dest_size);
-}
diff --git a/core/fpdfapi/parser/fpdf_parser_decode.h b/core/fpdfapi/parser/fpdf_parser_decode.h
index 6e146b5..757f4cf 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode.h
+++ b/core/fpdfapi/parser/fpdf_parser_decode.h
@@ -52,12 +52,6 @@
     int bpc,
     const CPDF_Dictionary* pParams);
 
-DataVector<uint8_t> FlateEncode(pdfium::span<const uint8_t> src_span);
-
-uint32_t FlateDecode(pdfium::span<const uint8_t> src_span,
-                     std::unique_ptr<uint8_t, FxFreeDeleter>* dest_buf,
-                     uint32_t* dest_size);
-
 uint32_t RunLengthDecode(pdfium::span<const uint8_t> src_span,
                          std::unique_ptr<uint8_t, FxFreeDeleter>* dest_buf,
                          uint32_t* dest_size);
diff --git a/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp b/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
index a67d7e2..6b3bc1e 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
+++ b/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
@@ -297,76 +297,6 @@
   }
 }
 
-// NOTE: python's zlib.compress() and zlib.decompress() may be useful for
-// external validation of the FlateDncode/FlateEecode test cases.
-TEST(FPDFParserDecodeEmbedderTest, FlateDecode) {
-  static const pdfium::DecodeTestData flate_decode_cases[] = {
-      STR_IN_OUT_CASE("", "", 0),
-      STR_IN_OUT_CASE("preposterous nonsense", "", 2),
-      STR_IN_OUT_CASE("\x78\x9c\x03\x00\x00\x00\x00\x01", "", 8),
-      STR_IN_OUT_CASE("\x78\x9c\x53\x00\x00\x00\x21\x00\x21", " ", 9),
-      STR_IN_OUT_CASE("\x78\x9c\x33\x34\x32\x06\x00\01\x2d\x00\x97", "123", 11),
-      STR_IN_OUT_CASE("\x78\x9c\x63\xf8\x0f\x00\x01\x01\x01\x00", "\x00\xff",
-                      10),
-      STR_IN_OUT_CASE(
-          "\x78\x9c\x33\x54\x30\x00\x42\x5d\x43\x05\x23\x4b\x05\x73\x33\x63"
-          "\x85\xe4\x5c\x2e\x90\x80\xa9\xa9\xa9\x82\xb9\xb1\xa9\x42\x51\x2a"
-          "\x57\xb8\x42\x1e\x57\x21\x92\xa0\x89\x9e\xb1\xa5\x09\x92\x84\x9e"
-          "\x85\x81\x81\x25\xd8\x14\x24\x26\xd0\x18\x43\x05\x10\x0c\x72\x57"
-          "\x80\x30\x8a\xd2\xb9\xf4\xdd\x0d\x14\xd2\x8b\xc1\x46\x99\x59\x1a"
-          "\x2b\x58\x1a\x9a\x83\x8c\x49\xe3\x0a\x04\x42\x00\x37\x4c\x1b\x42",
-          "1 0 0 -1 29 763 cm\n0 0 555 735 re\nW n\nq\n0 0 555 734.394 re\n"
-          "W n\nq\n0.8009 0 0 0.8009 0 0 cm\n1 1 1 RG 1 1 1 rg\n/G0 gs\n"
-          "0 0 693 917 re\nf\nQ\nQ\n",
-          96),
-  };
-
-  for (size_t i = 0; i < std::size(flate_decode_cases); ++i) {
-    const pdfium::DecodeTestData& data = flate_decode_cases[i];
-    std::unique_ptr<uint8_t, FxFreeDeleter> buf;
-    uint32_t buf_size;
-    EXPECT_EQ(data.processed_size,
-              FlateDecode({data.input, data.input_size}, &buf, &buf_size))
-        << " for case " << i;
-    ASSERT_TRUE(buf);
-    EXPECT_EQ(data.expected_size, buf_size) << " for case " << i;
-    if (data.expected_size != buf_size)
-      continue;
-    EXPECT_EQ(0, memcmp(data.expected, buf.get(), data.expected_size))
-        << " for case " << i;
-  }
-}
-
-TEST(ParserDecodeTest, FlateEncode) {
-  static const pdfium::StrFuncTestData flate_encode_cases[] = {
-      STR_IN_OUT_CASE("", "\x78\x9c\x03\x00\x00\x00\x00\x01"),
-      STR_IN_OUT_CASE(" ", "\x78\x9c\x53\x00\x00\x00\x21\x00\x21"),
-      STR_IN_OUT_CASE("123", "\x78\x9c\x33\x34\x32\x06\x00\01\x2d\x00\x97"),
-      STR_IN_OUT_CASE("\x00\xff", "\x78\x9c\x63\xf8\x0f\x00\x01\x01\x01\x00"),
-      STR_IN_OUT_CASE(
-          "1 0 0 -1 29 763 cm\n0 0 555 735 re\nW n\nq\n0 0 555 734.394 re\n"
-          "W n\nq\n0.8009 0 0 0.8009 0 0 cm\n1 1 1 RG 1 1 1 rg\n/G0 gs\n"
-          "0 0 693 917 re\nf\nQ\nQ\n",
-          "\x78\x9c\x4d\x8c\x3b\x0e\x80\x20\x10\x05\xfb\x3d\xc5\xbb\x80\xb8"
-          "\xc8\xcf\x3d\x01\x35\x36\x1e\x80\x28\x15\x26\xe2\xfd\x13\x83\x36"
-          "\xe4\x35\x93\x79\xc9\x68\x30\x18\x93\xc6\x22\x08\xde\x20\x57\xea"
-          "\xc2\x39\x87\x60\x1c\xda\x41\x3b\x2e\xba\x07\x69\x95\x11\x3b\x1c"
-          "\x6a\x65\x96\xaf\x32\x60\xae\xa4\xd1\xb7\x45\xfc\xd0\x0a\xcd\x91"
-          "\x51\x9e\x2f\xe5\xc5\x40\x74\xe8\x99\x93\x12\x25\x7a\x01\x37\x4c"
-          "\x1b\x42"),
-  };
-
-  for (size_t i = 0; i < std::size(flate_encode_cases); ++i) {
-    const pdfium::StrFuncTestData& data = flate_encode_cases[i];
-    DataVector<uint8_t> result = FlateEncode({data.input, data.input_size});
-    EXPECT_EQ(data.expected_size, result.size()) << " for case " << i;
-    if (data.expected_size != result.size())
-      continue;
-    EXPECT_EQ(0, memcmp(data.expected, result.data(), data.expected_size))
-        << " for case " << i;
-  }
-}
-
 TEST(ParserDecodeTest, HexDecode) {
   const pdfium::DecodeTestData kTestData[] = {
       // Empty src string.
diff --git a/core/fxcodec/BUILD.gn b/core/fxcodec/BUILD.gn
index deee958..8f4feb7 100644
--- a/core/fxcodec/BUILD.gn
+++ b/core/fxcodec/BUILD.gn
@@ -140,6 +140,7 @@
   sources = [
     "basic/a85_unittest.cpp",
     "basic/rle_unittest.cpp",
+    "flate/flatemodule_unittest.cpp",
     "jbig2/JBig2_BitStream_unittest.cpp",
     "jbig2/JBig2_Image_unittest.cpp",
     "jpx/jpx_unittest.cpp",
diff --git a/core/fxcodec/flate/flatemodule_unittest.cpp b/core/fxcodec/flate/flatemodule_unittest.cpp
new file mode 100644
index 0000000..939b4e7
--- /dev/null
+++ b/core/fxcodec/flate/flatemodule_unittest.cpp
@@ -0,0 +1,82 @@
+// Copyright 2023 The PDFium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/fxcodec/flate/flatemodule.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/test_support.h"
+
+// NOTE: python's zlib.compress() and zlib.decompress() may be useful for
+// external validation of the FlateDncode/FlateEecode test cases.
+TEST(FlateModule, Decode) {
+  static const pdfium::DecodeTestData flate_decode_cases[] = {
+      STR_IN_OUT_CASE("", "", 0),
+      STR_IN_OUT_CASE("preposterous nonsense", "", 2),
+      STR_IN_OUT_CASE("\x78\x9c\x03\x00\x00\x00\x00\x01", "", 8),
+      STR_IN_OUT_CASE("\x78\x9c\x53\x00\x00\x00\x21\x00\x21", " ", 9),
+      STR_IN_OUT_CASE("\x78\x9c\x33\x34\x32\x06\x00\01\x2d\x00\x97", "123", 11),
+      STR_IN_OUT_CASE("\x78\x9c\x63\xf8\x0f\x00\x01\x01\x01\x00", "\x00\xff",
+                      10),
+      STR_IN_OUT_CASE(
+          "\x78\x9c\x33\x54\x30\x00\x42\x5d\x43\x05\x23\x4b\x05\x73\x33\x63"
+          "\x85\xe4\x5c\x2e\x90\x80\xa9\xa9\xa9\x82\xb9\xb1\xa9\x42\x51\x2a"
+          "\x57\xb8\x42\x1e\x57\x21\x92\xa0\x89\x9e\xb1\xa5\x09\x92\x84\x9e"
+          "\x85\x81\x81\x25\xd8\x14\x24\x26\xd0\x18\x43\x05\x10\x0c\x72\x57"
+          "\x80\x30\x8a\xd2\xb9\xf4\xdd\x0d\x14\xd2\x8b\xc1\x46\x99\x59\x1a"
+          "\x2b\x58\x1a\x9a\x83\x8c\x49\xe3\x0a\x04\x42\x00\x37\x4c\x1b\x42",
+          "1 0 0 -1 29 763 cm\n0 0 555 735 re\nW n\nq\n0 0 555 734.394 re\n"
+          "W n\nq\n0.8009 0 0 0.8009 0 0 cm\n1 1 1 RG 1 1 1 rg\n/G0 gs\n"
+          "0 0 693 917 re\nf\nQ\nQ\n",
+          96),
+  };
+
+  for (size_t i = 0; i < std::size(flate_decode_cases); ++i) {
+    const pdfium::DecodeTestData& data = flate_decode_cases[i];
+    std::unique_ptr<uint8_t, FxFreeDeleter> buf;
+    uint32_t buf_size;
+    EXPECT_EQ(data.processed_size, FlateModule::FlateOrLZWDecode(
+                                       false, {data.input, data.input_size},
+                                       false, 0, 0, 0, 0, 0, &buf, &buf_size))
+        << " for case " << i;
+    ASSERT_TRUE(buf);
+    EXPECT_EQ(data.expected_size, buf_size) << " for case " << i;
+    if (data.expected_size != buf_size) {
+      continue;
+    }
+    EXPECT_EQ(0, memcmp(data.expected, buf.get(), data.expected_size))
+        << " for case " << i;
+  }
+}
+
+TEST(FlateModule, Encode) {
+  static const pdfium::StrFuncTestData flate_encode_cases[] = {
+      STR_IN_OUT_CASE("", "\x78\x9c\x03\x00\x00\x00\x00\x01"),
+      STR_IN_OUT_CASE(" ", "\x78\x9c\x53\x00\x00\x00\x21\x00\x21"),
+      STR_IN_OUT_CASE("123", "\x78\x9c\x33\x34\x32\x06\x00\01\x2d\x00\x97"),
+      STR_IN_OUT_CASE("\x00\xff", "\x78\x9c\x63\xf8\x0f\x00\x01\x01\x01\x00"),
+      STR_IN_OUT_CASE(
+          "1 0 0 -1 29 763 cm\n0 0 555 735 re\nW n\nq\n0 0 555 734.394 re\n"
+          "W n\nq\n0.8009 0 0 0.8009 0 0 cm\n1 1 1 RG 1 1 1 rg\n/G0 gs\n"
+          "0 0 693 917 re\nf\nQ\nQ\n",
+          "\x78\x9c\x4d\x8c\x3b\x0e\x80\x20\x10\x05\xfb\x3d\xc5\xbb\x80\xb8"
+          "\xc8\xcf\x3d\x01\x35\x36\x1e\x80\x28\x15\x26\xe2\xfd\x13\x83\x36"
+          "\xe4\x35\x93\x79\xc9\x68\x30\x18\x93\xc6\x22\x08\xde\x20\x57\xea"
+          "\xc2\x39\x87\x60\x1c\xda\x41\x3b\x2e\xba\x07\x69\x95\x11\x3b\x1c"
+          "\x6a\x65\x96\xaf\x32\x60\xae\xa4\xd1\xb7\x45\xfc\xd0\x0a\xcd\x91"
+          "\x51\x9e\x2f\xe5\xc5\x40\x74\xe8\x99\x93\x12\x25\x7a\x01\x37\x4c"
+          "\x1b\x42"),
+  };
+
+  for (size_t i = 0; i < std::size(flate_encode_cases); ++i) {
+    const pdfium::StrFuncTestData& data = flate_encode_cases[i];
+    DataVector<uint8_t> result =
+        FlateModule::Encode({data.input, data.input_size});
+    EXPECT_EQ(data.expected_size, result.size()) << " for case " << i;
+    if (data.expected_size != result.size()) {
+      continue;
+    }
+    EXPECT_EQ(0, memcmp(data.expected, result.data(), data.expected_size))
+        << " for case " << i;
+  }
+}