diff --git a/src/rpc/util.h b/src/rpc/util.h
--- a/src/rpc/util.h
+++ b/src/rpc/util.h
@@ -87,6 +87,9 @@
 UniValue JSONRPCTransactionError(TransactionError terr,
                                  const std::string &err_string = "");
 
+//! Parse a JSON range specified as int64, or [int64, int64]
+std::pair<int64_t, int64_t> ParseRange(const UniValue &value);
+
 struct RPCArg {
     enum class Type {
         OBJ,
diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -683,3 +683,21 @@
     }
     assert(false);
 }
+
+std::pair<int64_t, int64_t> ParseRange(const UniValue &value) {
+    if (value.isNum()) {
+        return {0, value.get_int64()};
+    }
+    if (value.isArray() && value.size() == 2 && value[0].isNum() &&
+        value[1].isNum()) {
+        int64_t low = value[0].get_int64();
+        int64_t high = value[1].get_int64();
+        if (low > high)
+            throw JSONRPCError(
+                RPC_INVALID_PARAMETER,
+                "Range specified as [begin,end] must not have begin after end");
+        return {low, high};
+    }
+    throw JSONRPCError(RPC_INVALID_PARAMETER,
+                       "Range must be specified as end or as [begin,end]");
+}