diff --git a/libqpdf/QPDFJob.cc b/libqpdf/QPDFJob.cc
index 621e693..55bebdc 100644
--- a/libqpdf/QPDFJob.cc
+++ b/libqpdf/QPDFJob.cc
@@ -1188,6 +1188,12 @@ QPDFJob::doJSONQpdf(Pipeline* p, bool& first, QPDF& pdf)
         p, first_qpdf, "jsonversion", JSON::makeInt(this->m->json_version), 1);
     JSON::writeDictionaryItem(
         p, first_qpdf, "pdfversion", JSON::makeString(pdf.getPDFVersion()), 1);
+    JSON::writeDictionaryItem(
+        p,
+        first_qpdf,
+        "maxobjectid",
+        JSON::makeInt(QIntC::to_longlong(pdf.getObjectCount())),
+        1);
     JSON::writeDictionaryKey(p, first_qpdf, "objects", 1);
     bool first_object = true;
     JSON::writeDictionaryOpen(p, first_object, 2);
@@ -1613,6 +1619,7 @@ QPDFJob::json_schema(int json_version, std::set<std::string>* keys)
             schema.addDictionaryMember("qpdf", JSON::parse(R"({
   "jsonversion": "qpdf json output version",
   "pdfversion": "PDF version from PDF header",
+  "maxobjectid": "Highest object ID; needed for adding new objects",
   "objects": {
     "<obj:n n R|trailer>": "json representation of object"
   }
diff --git a/qpdf/qtest/qpdf/direct-pages-json-objects.out b/qpdf/qtest/qpdf/direct-pages-json-objects.out
index 773a0a4..0746a92 100644
--- a/qpdf/qtest/qpdf/direct-pages-json-objects.out
+++ b/qpdf/qtest/qpdf/direct-pages-json-objects.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 6,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/direct-pages-json-pages.out b/qpdf/qtest/qpdf/direct-pages-json-pages.out
index 5cd2b2c..9f9e41f 100644
--- a/qpdf/qtest/qpdf/direct-pages-json-pages.out
+++ b/qpdf/qtest/qpdf/direct-pages-json-pages.out
@@ -28,6 +28,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 8,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/image-streams-small-to-json.out b/qpdf/qtest/qpdf/image-streams-small-to-json.out
index fa4929f..3fd3e14 100644
--- a/qpdf/qtest/qpdf/image-streams-small-to-json.out
+++ b/qpdf/qtest/qpdf/image-streams-small-to-json.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-bad-data-json-file-v2.out b/qpdf/qtest/qpdf/json-bad-data-json-file-v2.out
index 147dc37..79e739e 100644
--- a/qpdf/qtest/qpdf/json-bad-data-json-file-v2.out
+++ b/qpdf/qtest/qpdf/json-bad-data-json-file-v2.out
@@ -53,6 +53,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 6,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-bad-data-json-inline-v2.out b/qpdf/qtest/qpdf/json-bad-data-json-inline-v2.out
index bfd7ad3..8c65e1c 100644
--- a/qpdf/qtest/qpdf/json-bad-data-json-inline-v2.out
+++ b/qpdf/qtest/qpdf/json-bad-data-json-inline-v2.out
@@ -53,6 +53,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 6,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-field-types---show-encryption-key-v2.out b/qpdf/qtest/qpdf/json-field-types---show-encryption-key-v2.out
index c3158fa..d494860 100644
--- a/qpdf/qtest/qpdf/json-field-types---show-encryption-key-v2.out
+++ b/qpdf/qtest/qpdf/json-field-types---show-encryption-key-v2.out
@@ -434,6 +434,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.5",
+    "maxobjectid": 196,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-field-types-v2.out b/qpdf/qtest/qpdf/json-field-types-v2.out
index c3158fa..d494860 100644
--- a/qpdf/qtest/qpdf/json-field-types-v2.out
+++ b/qpdf/qtest/qpdf/json-field-types-v2.out
@@ -434,6 +434,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.5",
+    "maxobjectid": 196,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-all-file-v2.out b/qpdf/qtest/qpdf/json-image-streams-all-file-v2.out
index 9848651..728f404 100644
--- a/qpdf/qtest/qpdf/json-image-streams-all-file-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-all-file-v2.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:12 0 R": {
         "stream": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-all-v2.out b/qpdf/qtest/qpdf/json-image-streams-all-v2.out
index 6ba1541..423103a 100644
--- a/qpdf/qtest/qpdf/json-image-streams-all-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-all-v2.out
@@ -277,6 +277,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-generalized-file-v2.out b/qpdf/qtest/qpdf/json-image-streams-generalized-file-v2.out
index 00e5e8a..51258ec 100644
--- a/qpdf/qtest/qpdf/json-image-streams-generalized-file-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-generalized-file-v2.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:12 0 R": {
         "stream": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-generalized-inline-v2.out b/qpdf/qtest/qpdf/json-image-streams-generalized-inline-v2.out
index f84e478..1f28df1 100644
--- a/qpdf/qtest/qpdf/json-image-streams-generalized-inline-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-generalized-inline-v2.out
@@ -277,6 +277,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-none-file-v2.out b/qpdf/qtest/qpdf/json-image-streams-none-file-v2.out
index ce9ccda..d1b4090 100644
--- a/qpdf/qtest/qpdf/json-image-streams-none-file-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-none-file-v2.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:12 0 R": {
         "stream": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-none-inline-v2.out b/qpdf/qtest/qpdf/json-image-streams-none-inline-v2.out
index d275ed0..7559e5c 100644
--- a/qpdf/qtest/qpdf/json-image-streams-none-inline-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-none-inline-v2.out
@@ -277,6 +277,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-small-v2.out b/qpdf/qtest/qpdf/json-image-streams-small-v2.out
index f7556d3..8b0232a 100644
--- a/qpdf/qtest/qpdf/json-image-streams-small-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-small-v2.out
@@ -277,6 +277,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-specialized-file-v2.out b/qpdf/qtest/qpdf/json-image-streams-specialized-file-v2.out
index e086527..dcf1d47 100644
--- a/qpdf/qtest/qpdf/json-image-streams-specialized-file-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-specialized-file-v2.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:12 0 R": {
         "stream": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-specialized-inline-v2.out b/qpdf/qtest/qpdf/json-image-streams-specialized-inline-v2.out
index 082743d..451ca08 100644
--- a/qpdf/qtest/qpdf/json-image-streams-specialized-inline-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-specialized-inline-v2.out
@@ -277,6 +277,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-specialized-v2.out b/qpdf/qtest/qpdf/json-image-streams-specialized-v2.out
index 3e3f699..987d62c 100644
--- a/qpdf/qtest/qpdf/json-image-streams-specialized-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-specialized-v2.out
@@ -277,6 +277,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-image-streams-v2.out b/qpdf/qtest/qpdf/json-image-streams-v2.out
index 6a49225..64fc4cb 100644
--- a/qpdf/qtest/qpdf/json-image-streams-v2.out
+++ b/qpdf/qtest/qpdf/json-image-streams-v2.out
@@ -277,6 +277,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 30,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-outlines-with-actions-v2.out b/qpdf/qtest/qpdf/json-outlines-with-actions-v2.out
index feffede..4adc6a3 100644
--- a/qpdf/qtest/qpdf/json-outlines-with-actions-v2.out
+++ b/qpdf/qtest/qpdf/json-outlines-with-actions-v2.out
@@ -622,6 +622,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 108,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-outlines-with-old-root-dests-v2.out b/qpdf/qtest/qpdf/json-outlines-with-old-root-dests-v2.out
index 6ce3b54..8e97c09 100644
--- a/qpdf/qtest/qpdf/json-outlines-with-old-root-dests-v2.out
+++ b/qpdf/qtest/qpdf/json-outlines-with-old-root-dests-v2.out
@@ -727,6 +727,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 107,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-2-v2.out b/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-2-v2.out
index 814579f..867f5b9 100644
--- a/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-2-v2.out
+++ b/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-2-v2.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 106,
     "objects": {
       "obj:2 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-v2.out b/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-v2.out
index 63596e8..6a4969d 100644
--- a/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-v2.out
+++ b/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-trailer-v2.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 106,
     "objects": {
       "trailer": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-v2.out b/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-v2.out
index 3d8a2d6..9c8e5b5 100644
--- a/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-v2.out
+++ b/qpdf/qtest/qpdf/json-page-labels-and-outlines-qpdf-v2.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 106,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-page-labels-and-outlines-v2.out b/qpdf/qtest/qpdf/json-page-labels-and-outlines-v2.out
index 349b8b6..81f7441 100644
--- a/qpdf/qtest/qpdf/json-page-labels-and-outlines-v2.out
+++ b/qpdf/qtest/qpdf/json-page-labels-and-outlines-v2.out
@@ -797,6 +797,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 106,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/json-page-labels-num-tree-v2.out b/qpdf/qtest/qpdf/json-page-labels-num-tree-v2.out
index acff306..e7ea1ed 100644
--- a/qpdf/qtest/qpdf/json-page-labels-num-tree-v2.out
+++ b/qpdf/qtest/qpdf/json-page-labels-num-tree-v2.out
@@ -540,6 +540,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 99,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/page_api_2-json-objects.out b/qpdf/qtest/qpdf/page_api_2-json-objects.out
index b686d14..42d4712 100644
--- a/qpdf/qtest/qpdf/page_api_2-json-objects.out
+++ b/qpdf/qtest/qpdf/page_api_2-json-objects.out
@@ -6,6 +6,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 10,
     "objects": {
       "obj:1 0 R": {
         "value": {
diff --git a/qpdf/qtest/qpdf/page_api_2-json-pages.out b/qpdf/qtest/qpdf/page_api_2-json-pages.out
index 8e6f94b..372a14f 100644
--- a/qpdf/qtest/qpdf/page_api_2-json-pages.out
+++ b/qpdf/qtest/qpdf/page_api_2-json-pages.out
@@ -38,6 +38,7 @@
   "qpdf": {
     "jsonversion": 2,
     "pdfversion": "1.3",
+    "maxobjectid": 11,
     "objects": {
       "obj:1 0 R": {
         "value": {