diff --git a/Makefile b/Makefile
index f43e0e9d..f2cea23b 100644
--- a/Makefile
+++ b/Makefile
@@ -39,7 +39,7 @@ endif
 
 CHIBI_COMPILED_LIBS = lib/chibi/filesystem$(SO) lib/chibi/weak$(SO) \
 	lib/chibi/heap-stats$(SO) lib/chibi/disasm$(SO) lib/chibi/ast$(SO) \
-	lib/chibi/emscripten$(SO)
+	lib/chibi/json$(SO) lib/chibi/emscripten$(SO)
 CHIBI_POSIX_COMPILED_LIBS = lib/chibi/process$(SO) lib/chibi/time$(SO) \
 	lib/chibi/system$(SO) lib/chibi/stty$(SO) lib/chibi/pty$(SO) \
 	lib/chibi/net$(SO)
diff --git a/lib/chibi/json-test.sld b/lib/chibi/json-test.sld
new file mode 100644
index 00000000..69eefd63
--- /dev/null
+++ b/lib/chibi/json-test.sld
@@ -0,0 +1,64 @@
+
+(define-library (chibi json-test)
+  (import (scheme base) (chibi json) (chibi test))
+  (export run-tests)
+  (begin
+    (define (run-tests)
+      (test-begin "json")
+      (test '((glossary
+               (title . "example glossary")
+               (GlossDiv
+                (title . "S")
+                (GlossList
+                 (GlossEntry
+                  (ID . "SGML")
+                  (SortAs . "SGML")
+                  (GlossTerm . "Standard Generalized Markup Language")
+                  (Acronym . "SGML")
+                  (Abbrev . "ISO 8879:1986")
+                  (GlossDef
+                   (para . "A meta-markup language, used to create markup languages such as DocBook.")
+                   (GlossSeeAlso . #("GML" "XML")))
+                  (GlossSee . "markup"))))))
+          (parse-json "{
+    \"glossary\": {
+        \"title\": \"example glossary\",
+		\"GlossDiv\": {
+            \"title\": \"S\",
+			\"GlossList\": {
+                \"GlossEntry\": {
+                    \"ID\": \"SGML\",
+					\"SortAs\": \"SGML\",
+					\"GlossTerm\": \"Standard Generalized Markup Language\",
+					\"Acronym\": \"SGML\",
+					\"Abbrev\": \"ISO 8879:1986\",
+					\"GlossDef\": {
+                        \"para\": \"A meta-markup language, used to create markup languages such as DocBook.\",
+						\"GlossSeeAlso\": [\"GML\", \"XML\"]
+                    },
+					\"GlossSee\": \"markup\"
+                }
+            }
+        }
+    }
+}"))
+      (test '((menu
+               (id . "file")
+               (value . "File")
+               (popup
+                (menuitem
+                 . #(((value . "New") (onclick . "CreateNewDoc()"))
+                     ((value . "Open") (onclick . "OpenDoc()"))
+                     ((value . "Close") (onclick . "CloseDoc()")))))))
+          (parse-json "{\"menu\": {
+  \"id\": \"file\",
+  \"value\": \"File\",
+  \"popup\": {
+    \"menuitem\": [
+      {\"value\": \"New\", \"onclick\": \"CreateNewDoc()\"},
+      {\"value\": \"Open\", \"onclick\": \"OpenDoc()\"},
+      {\"value\": \"Close\", \"onclick\": \"CloseDoc()\"}
+    ]
+  }
+}}"))
+      (test-end))))
diff --git a/lib/chibi/json.c b/lib/chibi/json.c
new file mode 100644
index 00000000..178bcbfc
--- /dev/null
+++ b/lib/chibi/json.c
@@ -0,0 +1,251 @@
+/*  json.c -- fast json parser                           */
+/*  Copyright (c) 2019 Alex Shinn.  All rights reserved. */
+/*  BSD-style license: http://synthcode.com/license.txt  */
+
+#include <chibi/eval.h>
+
+sexp parse_json (sexp ctx, sexp self, sexp str, const char* s, int* i, const int len);
+
+sexp sexp_json_exception (sexp ctx, sexp self, const char* msg, sexp str, const int pos) {
+  sexp_gc_var2(res, tmp);
+  sexp_gc_preserve2(ctx, res, tmp);
+  tmp = sexp_list2(ctx, str, sexp_make_fixnum(pos));
+  res = sexp_user_exception(ctx, self, msg, tmp);
+  sexp_gc_release2(ctx);
+  return res;
+}
+
+sexp parse_json_number (sexp ctx, sexp self, sexp str, const char* s, int* i, const int len) {
+  sexp_sint_t res = 0;
+  int j = *i;
+  while (j < len && isdigit(s[j]))
+    res = res * 10 + s[j++] - '0';
+  *i = j;
+  return sexp_make_fixnum(res);
+}
+
+sexp parse_json_literal (sexp ctx, sexp self, sexp str, const char* s, int* i, const int len, const char* name, int namelen, sexp value) {
+  sexp res;
+  if (strncasecmp(s+*i, name, namelen) == 0 && (*i+namelen >= len || !isalnum(s[*i+namelen]))) {
+    res = value;
+    *i += namelen;
+  } else {
+    res = sexp_json_exception(ctx, self, "unexpected character in json at", str, *i);
+  }
+  return res;
+}
+
+sexp parse_json_string (sexp ctx, sexp self, sexp str, const char* s, int* i, const int len) {
+  sexp_gc_var2(res, tmp);
+  sexp_gc_preserve2(ctx, res, tmp);
+  int from = *i, to = *i;
+  res = SEXP_NULL;
+  for ( ; s[to] != '"'; ++to) {
+    if (to+1 >= len) {
+      res = sexp_json_exception(ctx, self, "unterminated string in json started at", str, *i);
+      break;
+    }
+    if (s[to] == '\\') {
+      tmp = sexp_c_string(ctx, s+from, to-from);
+      res = sexp_stringp(res) ? sexp_list2(ctx, tmp, res) : sexp_cons(ctx, tmp, res);
+      switch (s[++to]) {
+      case 'n':
+        tmp = sexp_c_string(ctx, "\n", -1);
+        res = sexp_cons(ctx, tmp, res);
+        from = to+1;
+        break;
+      case 't':
+        tmp = sexp_c_string(ctx, "\t", -1);
+        res = sexp_cons(ctx, tmp, res);
+        from = to+1;
+        break;
+      default:
+        from = to;
+        break;
+      }
+    }
+  }
+  if (!sexp_exceptionp(res)) {
+    tmp = sexp_c_string(ctx, s+from, to-from);
+    if (res == SEXP_NULL) {
+      res = tmp;
+    } else {
+      res = sexp_stringp(res) ? sexp_list2(ctx, tmp, res) : sexp_cons(ctx, tmp, res);
+      res = sexp_nreverse(ctx, res);
+      res = sexp_string_concatenate(ctx, res, SEXP_FALSE);
+    }
+  }
+  *i = to+1;
+  sexp_gc_release2(ctx);
+  return res;
+}
+
+sexp parse_json_array (sexp ctx, sexp self, sexp str, const char* s, int* i, const int len) {
+  sexp_gc_var2(res, tmp);
+  sexp_gc_preserve2(ctx, res, tmp);
+  int j = *i;
+  int comma = 1;
+  res = SEXP_NULL;
+  while (1) {
+    if (j >= len) {
+      res = sexp_json_exception(ctx, self, "unterminated array in json started at", str, *i);
+      break;
+    } else if (s[j] == ']') {
+      if (comma && res != SEXP_NULL) {
+        res = sexp_json_exception(ctx, self, "missing value after comma in json array at", str, j);
+      } else {
+        res = sexp_nreverse(ctx, res);
+        res = sexp_list_to_vector(ctx, res);
+      }
+      ++j;
+      break;
+    } else if (s[j] == ',' && comma) {
+      res = sexp_json_exception(ctx, self, "unexpected comma in json array at", str, j);
+      break;
+    } else if (s[j] == ',') {
+      comma = 1;
+      ++j;
+    } else if (isspace(s[j])) {
+      ++j;
+    } else {
+      if (comma) {
+        tmp = parse_json(ctx, self, str, s, &j, len);
+        if (sexp_exceptionp(tmp)) {
+          res = tmp;
+          break;
+        }
+        res = sexp_cons(ctx, tmp, res);
+        comma = 0;
+      } else {
+        res = sexp_json_exception(ctx, self, "unexpected value in json array at", str, j);
+        break;
+      }
+    }
+  }
+  *i = j;
+  sexp_gc_release2(ctx);
+  return res;
+}
+
+sexp parse_json_object (sexp ctx, sexp self, sexp str, const char* s, int* i, const int len) {
+  sexp_gc_var2(res, tmp);
+  sexp_gc_preserve2(ctx, res, tmp);
+  int j = *i;
+  int comma = 1;
+  res = SEXP_NULL;
+  while (1) {
+    if (j >= len) {
+      res = sexp_json_exception(ctx, self, "unterminated object in json started at", str, *i);
+      break;
+    } else if (s[j] == '}') {
+      if (comma && res != SEXP_NULL) {
+        res = sexp_json_exception(ctx, self, "missing value after comma in json object at", str, j);
+      } else {
+        res = sexp_nreverse(ctx, res);
+      }
+      ++j;
+      break;
+    } else if (s[j] == ',' && comma) {
+      res = sexp_json_exception(ctx, self, "unexpected comma in json object at", str, j);
+      break;
+    } else if (s[j] == ',') {
+      comma = 1;
+      ++j;
+    } else if (isspace(s[j])) {
+      ++j;
+    } else {
+      if (comma) {
+        tmp = parse_json(ctx, self, str, s, &j, len);
+        if (sexp_exceptionp(tmp)) {
+          res = tmp;
+          break;
+        } else if (sexp_stringp(tmp)) {
+          tmp = sexp_string_to_symbol(ctx, tmp);
+        }
+        tmp = sexp_cons(ctx, tmp, SEXP_VOID);
+        while (j < len && isspace(s[j]))
+          ++j;
+        if (s[j] != ':') {
+          res = sexp_json_exception(ctx, self, "missing colon in json object at", str, j);
+          break;
+        }
+        ++j;
+        sexp_cdr(tmp) = parse_json(ctx, self, str, s, &j, len);
+        if (sexp_exceptionp(sexp_cdr(tmp))) {
+          res = sexp_cdr(tmp);
+          break;
+        }
+        res = sexp_cons(ctx, tmp, res);
+        comma = 0;
+      } else {
+        res = sexp_json_exception(ctx, self, "unexpected value in json object at", str, j);
+        break;
+      }
+    }
+  }
+  *i = j;
+  sexp_gc_release2(ctx);
+  return res;
+}
+
+sexp parse_json (sexp ctx, sexp self, sexp str, const char* s, int* i, const int len) {
+  sexp res;
+  int j = *i;
+  while (j < len && isspace(s[j]))
+    ++j;
+  switch (s[j]) {
+  case '{':
+    ++j;
+    res = parse_json_object(ctx, self, str, s, &j, len);
+    break;
+  case '[':
+    ++j;
+    res = parse_json_array(ctx, self, str, s, &j, len);
+    break;
+  case '"':
+    ++j;
+    res = parse_json_string(ctx, self, str, s, &j, len);
+    break;
+  case '0': case '1': case '2': case '3': case '4':
+  case '5': case '6': case '7': case '8': case '9':
+    res = parse_json_number(ctx, self, str, s, &j, len);
+    break;
+  case 'n': case 'N':
+    res = parse_json_literal(ctx, self, str, s, &j, len, "null", 4, SEXP_VOID);
+    break;
+  case 't': case 'T':
+    res = parse_json_literal(ctx, self, str, s, &j, len, "true", 4, SEXP_TRUE);
+    break;
+  case 'f': case 'F':
+    res = parse_json_literal(ctx, self, str, s, &j, len, "false", 5, SEXP_FALSE);
+    break;
+  case '}':
+    res = sexp_json_exception(ctx, self, "unexpected closing brace in json at", str, j);
+    break;
+  case ']':
+    res = sexp_json_exception(ctx, self, "unexpected closing bracket in json at", str, j);
+    break;
+  default:
+    res = sexp_json_exception(ctx, self, "unexpected character in json at", str, j);
+    break;
+  }
+  *i = j;
+  return res;
+}
+
+sexp sexp_parse_json (sexp ctx, sexp self, sexp_sint_t n, sexp str) {
+  const char *s;
+  int i=0, len;
+  sexp_assert_type(ctx, sexp_stringp, SEXP_STRING, str);
+  s = sexp_string_data(str);
+  len = sexp_string_size(str);
+  return parse_json(ctx, self, str, s, &i, len);
+}
+
+sexp sexp_init_library (sexp ctx, sexp self, sexp_sint_t n, sexp env, const char* version, const sexp_abi_identifier_t abi) {
+  if (!(sexp_version_compatible(ctx, version, sexp_version)
+        && sexp_abi_compatible(ctx, abi, SEXP_ABI_IDENTIFIER)))
+    return SEXP_ABI_ERROR;
+  sexp_define_foreign(ctx, env, "parse-json", 1, sexp_parse_json);
+  return SEXP_VOID;
+}
diff --git a/lib/chibi/json.sld b/lib/chibi/json.sld
new file mode 100644
index 00000000..d5043a93
--- /dev/null
+++ b/lib/chibi/json.sld
@@ -0,0 +1,5 @@
+
+(define-library (chibi json)
+  (import (scheme base))
+  (export parse-json)
+  (include-shared "json"))