Network Working Group                                       D. CrockfordRequest for Comments: 4627                                      JSON.orgCategory: Informational                                        July 2006 The application/json Media Type for JavaScript Object Notation (JSON)Status of This Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2006).Abstract   JavaScript Object Notation (JSON) is a lightweight, text-based,   language-independent data interchange format.  It was derived from   the ECMAScript Programming Language Standard.  JSON defines a small   set of formatting rules for the portable representation of structured   data.1.  Introduction   JavaScript Object Notation (JSON) is a text format for the   serialization of structured data.  It is derived from the object   literals of JavaScript, as defined in the ECMAScript Programming   Language Standard, Third Edition [ECMA].   JSON can represent four primitive types (strings, numbers, booleans,   and null) and two structured types (objects and arrays).   A string is a sequence of zero or more Unicode characters [UNICODE].   An object is an unordered collection of zero or more name/value   pairs, where a name is a string and a value is a string, number,   boolean, null, object, or array.   An array is an ordered sequence of zero or more values.   The terms "object" and "array" come from the conventions of   JavaScript.   JSON's design goals were for it to be minimal, portable, textual, and   a subset of JavaScript.Crockford                    Informational                      [Page 1]RFC 4627                          JSON                         July 20061.1.  Conventions Used in This Document   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described in [RFC2119].   The grammatical rules in this document are to be interpreted as   described in [RFC4234].2.  JSON Grammar   A JSON text is a sequence of tokens.  The set of tokens includes six   structural characters, strings, numbers, and three literal names.   A JSON text is a serialized object or array.      JSON-text = object / array   These are the six structural characters:      begin-array     = ws %x5B ws  ; [ left square bracket      begin-object    = ws %x7B ws  ; { left curly bracket      end-array       = ws %x5D ws  ; ] right square bracket      end-object      = ws %x7D ws  ; } right curly bracket      name-separator  = ws %x3A ws  ; : colon      value-separator = ws %x2C ws  ; , comma   Insignificant whitespace is allowed before or after any of the six   structural characters.      ws = *(                %x20 /              ; Space                %x09 /              ; Horizontal tab                %x0A /              ; Line feed or New line                %x0D                ; Carriage return            )2.1.  Values   A JSON value MUST be an object, array, number, or string, or one of   the following three literal names:      false null trueCrockford                    Informational                      [Page 2]RFC 4627                          JSON                         July 2006   The literal names MUST be lowercase.  No other literal names are   allowed.         value = false / null / true / object / array / number / string         false = %x66.61.6c.73.65   ; false         null  = %x6e.75.6c.6c      ; null         true  = %x74.72.75.65      ; true2.2.  Objects   An object structure is represented as a pair of curly brackets   surrounding zero or more name/value pairs (or members).  A name is a   string.  A single colon comes after each name, separating the name   from the value.  A single comma separates a value from a following   name.  The names within an object SHOULD be unique.      object = begin-object [ member *( value-separator member ) ]      end-object      member = string name-separator value2.3.  Arrays   An array structure is represented as square brackets surrounding zero   or more values (or elements).  Elements are separated by commas.      array = begin-array [ value *( value-separator value ) ] end-array2.4.  Numbers   The representation of numbers is similar to that used in most   programming languages.  A number contains an integer component that   may be prefixed with an optional minus sign, which may be followed by   a fraction part and/or an exponent part.   Octal and hex forms are not allowed.  Leading zeros are not allowed.   A fraction part is a decimal point followed by one or more digits.   An exponent part begins with the letter E in upper or lowercase,   which may be followed by a plus or minus sign.  The E and optional   sign are followed by one or more digits.   Numeric values that cannot be represented as sequences of digits   (such as Infinity and NaN) are not permitted.Crockford                    Informational                      [Page 3]RFC 4627                          JSON                         July 2006         number = [ minus ] int [ frac ] [ exp ]         decimal-point = %x2E       ; .         digit1-9 = %x31-39         ; 1-9         e = %x65 / %x45            ; e E         exp = e [ minus / plus ] 1*DIGIT         frac = decimal-point 1*DIGIT         int = zero / ( digit1-9 *DIGIT )         minus = %x2D               ; -         plus = %x2B                ; +         zero = %x30                ; 02.5.  Strings   The representation of strings is similar to conventions used in the C   family of programming languages.  A string begins and ends with   quotation marks.  All Unicode characters may be placed within the   quotation marks except for the characters that must be escaped:   quotation mark, reverse solidus, and the control characters (U+0000   through U+001F).   Any character may be escaped.  If the character is in the Basic   Multilingual Plane (U+0000 through U+FFFF), then it may be   represented as a six-character sequence: a reverse solidus, followed   by the lowercase letter u, followed by four hexadecimal digits that   encode the character's code point.  The hexadecimal letters A though   F can be upper or lowercase.  So, for example, a string containing   only a single reverse solidus character may be represented as   "\u005C".   Alternatively, there are two-character sequence escape   representations of some popular characters.  So, for example, a   string containing only a single reverse solidus character may be   represented more compactly as "\\".   To escape an extended character that is not in the Basic Multilingual   Plane, the character is represented as a twelve-character sequence,   encoding the UTF-16 surrogate pair.  So, for example, a string   containing only the G clef character (U+1D11E) may be represented as   "\uD834\uDD1E".Crockford                    Informational                      [Page 4]RFC 4627                          JSON                         July 2006         string = quotation-mark *char quotation-mark         char = unescaped /                escape (                    %x22 /          ; "    quotation mark  U+0022                    %x5C /          ; \    reverse solidus U+005C                    %x2F /          ; /    solidus         U+002F                    %x62 /          ; b    backspace       U+0008                    %x66 /          ; f    form feed       U+000C                    %x6E /          ; n    line feed       U+000A                    %x72 /          ; r    carriage return U+000D                    %x74 /          ; t    tab             U+0009                    %x75 4HEXDIG )  ; uXXXX                U+XXXX         escape = %x5C              ; \         quotation-mark = %x22      ; "         unescaped = %x20-21 / %x23-5B / %x5D-10FFFF3.  Encoding   JSON text SHALL be encoded in Unicode.  The default encoding is   UTF-8.   Since the first two characters of a JSON text will always be ASCII   characters [RFC0020], it is possible to determine whether an octet   stream is UTF-8, UTF-16 (BE or LE), or UTF-32 (BE or LE) by looking   at the pattern of nulls in the first four octets.           00 00 00 xx  UTF-32BE           00 xx 00 xx  UTF-16BE           xx 00 00 00  UTF-32LE           xx 00 xx 00  UTF-16LE           xx xx xx xx  UTF-84.  Parsers   A JSON parser transforms a JSON text into another representation.  A   JSON parser MUST accept all texts that conform to the JSON grammar.   A JSON parser MAY accept non-JSON forms or extensions.   An implementation may set limits on the size of texts that it   accepts.  An implementation may set limits on the maximum depth of   nesting.  An implementation may set limits on the range of numbers.   An implementation may set limits on the length and character contents   of strings.Crockford                    Informational                      [Page 5]RFC 4627                          JSON                         July 20065. Generators   A JSON generator produces JSON text.  The resulting text MUST   strictly conform to the JSON grammar.6. IANA Considerations   The MIME media type for JSON text is application/json.   Type name: application   Subtype name: json   Required parameters: n/a   Optional parameters: n/a   Encoding considerations: 8bit if UTF-8; binary if UTF-16 or UTF-32      JSON may be represented using UTF-8, UTF-16, or UTF-32.  When JSON      is written in UTF-8, JSON is 8bit compatible.  When JSON is      written in UTF-16 or UTF-32, the binary content-transfer-encoding      must be used.   Security considerations:   Generally there are security issues with scripting languages.  JSON   is a subset of JavaScript, but it is a safe subset that excludes   assignment and invocation.   A JSON text can be safely passed into JavaScript's eval() function   (which compiles and executes a string) if all the characters not   enclosed in strings are in the set of characters that form JSON   tokens.  This can be quickly determined in JavaScript with two   regular expressions and calls to the test and replace methods.      var my_JSON_object = !(/[^,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]/.test(             text.replace(/"(\\.|[^"\\])*"/g, ''))) &&         eval('(' + text + ')');   Interoperability considerations: n/a   Published specification: RFC 4627Crockford                    Informational                      [Page 6]RFC 4627                          JSON                         July 2006   Applications that use this media type:      JSON has been used to exchange data between applications written      in all of these programming languages: ActionScript, C, C#,      ColdFusion, Common Lisp, E, Erlang, Java, JavaScript, Lua,      Objective CAML, Perl, PHP, Python, Rebol, Ruby, and Scheme.   Additional information:      Magic number(s): n/a      File extension(s): .json      Macintosh file type code(s): TEXT   Person & email address to contact for further information:      Douglas Crockford      douglas@crockford.com   Intended usage: COMMON   Restrictions on usage: none   Author:      Douglas Crockford      douglas@crockford.com   Change controller:      Douglas Crockford      douglas@crockford.com7. Security Considerations   See Security Considerations in Section 6.8. Examples   This is a JSON object:   {      "Image": {          "Width":  800,          "Height": 600,          "Title":  "View from 15th Floor",          "Thumbnail": {              "Url":    "http://www.example.com/image/481989943",              "Height": 125,              "Width":  "100"          },          "IDs": [116, 943, 234, 38793]Crockford                    Informational                      [Page 7]RFC 4627                          JSON                         July 2006        }   }   Its Image member is an object whose Thumbnail member is an object   and whose IDs member is an array of numbers.   This is a JSON array containing two objects:   [      {         "precision": "zip",         "Latitude":  37.7668,         "Longitude": -122.3959,         "Address":   "",         "City":      "SAN FRANCISCO",         "State":     "CA",         "Zip":       "94107",         "Country":   "US"      },      {         "precision": "zip",         "Latitude":  37.371991,         "Longitude": -122.026020,         "Address":   "",         "City":      "SUNNYVALE",         "State":     "CA",         "Zip":       "94085",         "Country":   "US"      }   ]9. References9.1.  Normative References   [ECMA]    European Computer Manufacturers Association, "ECMAScript             Language Specification 3rd Edition", December 1999,             
    
     .   [RFC0020] Cerf, V., "ASCII format for network interchange", RFC 20,             October 1969.   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate             Requirement Levels", BCP 14, RFC 2119, March 1997.   [RFC4234] Crocker, D. and P.  Overell, "Augmented BNF for Syntax             Specifications: ABNF", RFC 4234, October 2005.Crockford                    Informational                      [Page 8]RFC 4627                          JSON                         July 2006   [UNICODE] The Unicode Consortium, "The Unicode Standard Version 4.0",             2003, 
     .Author's Address   Douglas Crockford   JSON.org   EMail: douglas@crockford.comCrockford                    Informational                      [Page 9]RFC 4627                          JSON                         July 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained in BCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found in BCP 78 and BCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository at   http://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).Crockford                    Informational                     [Page 10]