diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index f41905787..a67b7ae0d 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -6,12 +6,15 @@
 #include "globals.hh"
 #include "eval-inline.hh"
 #include "download.hh"
+#include "json.hh"
 
 #include <algorithm>
 #include <cstring>
 #include <unistd.h>
 #include <sys/time.h>
 #include <sys/resource.h>
+#include <iostream>
+#include <fstream>
 
 #include <sys/time.h>
 #include <sys/resource.h>
@@ -23,6 +26,7 @@
 
 #endif
 
+using std::cout;
 
 namespace nix {
 
@@ -1723,12 +1727,10 @@ bool EvalState::eqValues(Value & v1, Value & v2)
     }
 }
 
-
 void EvalState::printStats()
 {
     bool showStats = getEnv("NIX_SHOW_STATS", "0") != "0";
     Verbosity v = showStats ? lvlInfo : lvlDebug;
-    printMsg(v, "evaluation statistics:");
 
     struct rusage buf;
     getrusage(RUSAGE_SELF, &buf);
@@ -1739,34 +1741,69 @@ void EvalState::printStats()
     uint64_t bValues = nrValues * sizeof(Value);
     uint64_t bAttrsets = nrAttrsets * sizeof(Bindings) + nrAttrsInAttrsets * sizeof(Attr);
 
-    printMsg(v, format("  time elapsed: %1%") % cpuTime);
-    printMsg(v, format("  size of a value: %1%") % sizeof(Value));
-    printMsg(v, format("  size of an attr: %1%") % sizeof(Attr));
-    printMsg(v, format("  environments allocated count: %1%") % nrEnvs);
-    printMsg(v, format("  environments allocated bytes: %1%") % bEnvs);
-    printMsg(v, format("  list elements count: %1%") % nrListElems);
-    printMsg(v, format("  list elements bytes: %1%") % bLists);
-    printMsg(v, format("  list concatenations: %1%") % nrListConcats);
-    printMsg(v, format("  values allocated count: %1%") % nrValues);
-    printMsg(v, format("  values allocated bytes: %1%") % bValues);
-    printMsg(v, format("  sets allocated: %1% (%2% bytes)") % nrAttrsets % bAttrsets);
-    printMsg(v, format("  right-biased unions: %1%") % nrOpUpdates);
-    printMsg(v, format("  values copied in right-biased unions: %1%") % nrOpUpdateValuesCopied);
-    printMsg(v, format("  symbols in symbol table: %1%") % symbols.size());
-    printMsg(v, format("  size of symbol table: %1%") % symbols.totalSize());
-    printMsg(v, format("  number of thunks: %1%") % nrThunks);
-    printMsg(v, format("  number of thunks avoided: %1%") % nrAvoided);
-    printMsg(v, format("  number of attr lookups: %1%") % nrLookups);
-    printMsg(v, format("  number of primop calls: %1%") % nrPrimOpCalls);
-    printMsg(v, format("  number of function calls: %1%") % nrFunctionCalls);
-    printMsg(v, format("  total allocations: %1% bytes") % (bEnvs + bLists + bValues + bAttrsets));
-
 #if HAVE_BOEHMGC
     GC_word heapSize, totalBytes;
     GC_get_heap_usage_safe(&heapSize, 0, 0, 0, &totalBytes);
-    printMsg(v, format("  current Boehm heap size: %1% bytes") % heapSize);
-    printMsg(v, format("  total Boehm heap allocations: %1% bytes") % totalBytes);
 #endif
+    if (showStats) {
+        printMsg(v, "evaluation statistics:");
+        auto outPath = getEnv("NIX_SHOW_STATS_PATH","-");
+        std::fstream fs;
+        if (outPath != "-") {
+            fs.open(outPath, std::fstream::out);
+            printMsg(v, format("  written to: %1%") % outPath);
+        }
+        JSONObject topObj(outPath == "-" ? cout : fs, true);
+        topObj.attr("cpuTime",cpuTime);
+        {
+            auto envs = topObj.object("envs");
+            envs.attr("number", nrEnvs);
+            envs.attr("elements", nrValuesInEnvs);
+            envs.attr("bytes", bEnvs);
+        }
+        {
+            auto lists = topObj.object("list");
+            lists.attr("elements", nrListElems);
+            lists.attr("bytes", bLists);
+            lists.attr("concats", nrListConcats);
+        }
+        {
+            auto values = topObj.object("values");
+            values.attr("number", nrValues);
+            values.attr("bytes", bValues);
+        }
+        {
+            auto syms = topObj.object("symbols");
+            syms.attr("number", symbols.size());
+            syms.attr("bytes", symbols.totalSize());
+        }
+        {
+            auto sets = topObj.object("sets");
+            sets.attr("number", nrAttrsets);
+            sets.attr("bytes", bAttrsets);
+            sets.attr("elements", nrAttrsInAttrsets);
+        }
+        {
+            JSONObject sizes = topObj.object("sizes");
+            sizes.attr("Env", sizeof(Env));
+            sizes.attr("Value", sizeof(Value));
+            sizes.attr("Bindings", sizeof(Bindings));
+            sizes.attr("Attr", sizeof(Attr));
+        }
+        topObj.attr("nrOpUpdates", nrOpUpdates);
+        topObj.attr("nrOpUpdateValuesCopied", nrOpUpdateValuesCopied);
+        topObj.attr("nrThunks", nrThunks);
+        topObj.attr("nrAvoided", nrAvoided);
+        topObj.attr("nrLookups", nrLookups);
+        topObj.attr("nrPrimOpCalls", nrPrimOpCalls);
+        topObj.attr("nrFunctionCalls", nrFunctionCalls);
+#if HAVE_BOEHMGC
+        JSONObject gc = topObj.object("gc");
+        gc.attr("heapSize", heapSize);
+        gc.attr("totalBytes", totalBytes);
+#endif
+    }
+
 
     if (countCalls) {
         v = lvlInfo;