With Python 2.6+ you can do:

echo '{"foo": "lorem", "bar": "ipsum"}' | python -m json.tool

or, if the JSON is in a file, you can do:

python -m json.tool my_json.json

if the JSON is from an internet source such as an API, you can use

curl http://my_url/ | python -m json.tool

For convenience in all of these cases you can make an alias:

alias prettyjson='python -m json.tool'

For even more convenience with a bit more typing to get it ready:

prettyjson_s() {
    echo "$1" | python -m json.tool
}

prettyjson_f() {
    python -m json.tool "$1"
}

prettyjson_w() {
    curl "$1" | python -m json.tool
}

for all the above cases. You can put this in .bashrc and it will be available every time in shell. Invoke it like prettyjson_s '{"foo": "lorem", "bar": "ipsum"}'.

Note that as @pnd pointed out in the comments below, in Python 3.5+ the JSON object is no longer sorted by default. To sort, add the --sort-keys flag to the end. I.e. ... | python -m json.tool --sort-keys.

You can use: jq

It's very simple to use and it works great! It can handle very large JSON structures, including streams. You can find their tutorials here.

Usage examples:

$ jq --color-output . file1.json file1.json | less -R

$ command_with_json_output | jq .

$ jq # stdin/"interactive" mode, just enter some JSON

$ jq <<< '{ "foo": "lorem", "bar": "ipsum" }'
{
  "bar": "ipsum",
  "foo": "lorem"
}

Or use jq with identity filter:

$ jq '.foo' <<< '{ "foo": "lorem", "bar": "ipsum" }'
"lorem"

I use the "space" argument of JSON.stringify to pretty-print JSON in JavaScript.

Examples:

// Indent with 4 spaces
JSON.stringify({"foo":"lorem","bar":"ipsum"}, null, 4);

// Indent with tabs
JSON.stringify({"foo":"lorem","bar":"ipsum"}, null, '\t');

From the Unix command-line with Node.js, specifying JSON on the command line:

$ node -e "console.log(JSON.stringify(JSON.parse(process.argv[1]), null, '\t'));" \
  '{"foo":"lorem","bar":"ipsum"}'

Returns:

{
    "foo": "lorem",
    "bar": "ipsum"
}

From the Unix command-line with Node.js, specifying a filename that contains JSON, and using an indent of four spaces:

$ node -e "console.log(JSON.stringify(JSON.parse(require('fs') \
      .readFileSync(process.argv[1])), null, 4));"  filename.json

Using a pipe:

echo '{"foo": "lorem", "bar": "ipsum"}' | node -e \
"\
 s=process.openStdin();\
 d=[];\
 s.on('data',function(c){\
   d.push(c);\
 });\
 s.on('end',function(){\
   console.log(JSON.stringify(JSON.parse(d.join('')),null,2));\
 });\
"

I wrote a tool that has one of the best "smart whitespace" formatters available. It produces more readable and less verbose output than most of the other options here.

underscore-cli

This is what "smart whitespace" looks like:

I may be a bit biased, but it's an awesome tool for printing and manipulating JSON data from the command-line. It's super-friendly to use and has extensive command-line help/documentation. It's a Swiss Army knife that I use for 1001 different small tasks that would be surprisingly annoying to do any other way.

Latest use-case: Chrome, Dev console, Network tab, export all as HAR file, "cat site.har | underscore select '.url' --outfmt text | grep mydomain"; now I have a chronologically ordered list of all URL fetches made during the loading of my company's site.

Pretty printing is easy:

underscore -i data.json print

Same thing:

cat data.json | underscore print

Same thing, more explicit:

cat data.json | underscore print --outfmt pretty

This tool is my current passion project, so if you have any feature requests, there is a good chance I'll address them.

I usually just do:

echo '{"test":1,"test2":2}' | python -mjson.tool

And to retrieve select data (in this case, "test"'s value):

echo '{"test":1,"test2":2}' | python -c 'import sys,json;data=json.loads(sys.stdin.read()); print data["test"]'

If the JSON data is in a file:

python -mjson.tool filename.json

If you want to do it all in one go with curl on the command line using an authentication token:

curl -X GET -H "Authorization: Token wef4fwef54te4t5teerdfgghrtgdg53" http://testsite/api/ | python -mjson.tool

If you use npm and Node.js, you can do npm install -g json and then pipe the command through json. Do json -h to get all the options. It can also pull out specific fields and colorize the output with -i.

curl -s http://search.twitter.com/search.json?q=node.js | json

It is not too simple with a native way with the jq tools.

For example:

cat xxx | jq .

Thanks to J.F. Sebastian's very helpful pointers, here's a slightly enhanced script I've come up with:

#!/usr/bin/python

"""
Convert JSON data to human-readable form.

Usage:
  prettyJSON.py inputFile [outputFile]
"""

import sys
import simplejson as json


def main(args):
    try:
        if args[1] == '-':
            inputFile = sys.stdin
        else:
            inputFile = open(args[1])
        input = json.load(inputFile)
        inputFile.close()
    except IndexError:
        usage()
        return False
    if len(args) < 3:
        print json.dumps(input, sort_keys = False, indent = 4)
    else:
        outputFile = open(args[2], "w")
        json.dump(input, outputFile, sort_keys = False, indent = 4)
        outputFile.close()
    return True


def usage():
    print __doc__


if __name__ == "__main__":
    sys.exit(not main(sys.argv))

a simple bash script for pretty json printing

json_pretty.sh

#/bin/bash

grep -Eo '"[^"]*" *(: *([0-9]*|"[^"]*")[^{}\["]*|,)?|[^"\]\[\}\{]*|\{|\},?|\[|\],?|[0-9 ]*,?' | awk '{if ($0 ~ /^[}\]]/ ) offset-=4; printf "%*c%s\n", offset, " ", $0; if ($0 ~ /^[{\[]/) offset+=4}'

Example:

cat file.json | json_pretty.sh

With Perl, use the CPAN module JSON::XS. It installs a command line tool json_xs.

Validate:

json_xs -t null < myfile.json

Prettify the JSON file src.json to pretty.json:

< src.json json_xs > pretty.json

If you don't have json_xs, try json_pp . "pp" is for "pure perl" – the tool is implemented in Perl only, without a binding to an external C library (which is what XS stands for, Perl's "Extension System").

On *nix, reading from stdin and writing to stdout works better:

#!/usr/bin/env python
"""
Convert JSON data to human-readable form.

(Reads from stdin and writes to stdout)
"""

import sys
try:
    import simplejson as json
except:
    import json

print json.dumps(json.loads(sys.stdin.read()), indent=4)
sys.exit(0)

Put this in a file (I named mine "prettyJSON" after AnC's answer) in your PATH and chmod +x it, and you're good to go.

That's how I do it:

curl yourUri | json_pp

It shortens the code and gets the job done.

The JSON Ruby Gem is bundled with a shell script to prettify JSON:

sudo gem install json
echo '{ "foo": "bar" }' | prettify_json.rb

Script download: gist.github.com/3738968

$ echo '{ "foo": "lorem", "bar": "ipsum" }' \
> | python -c'import fileinput, json;
> print(json.dumps(json.loads("".join(fileinput.input())),
>                  sort_keys=True, indent=4))'
{
    "bar": "ipsum",
    "foo": "lorem"
}

NOTE: It is not the way to do it.

The same in Perl:

$ cat json.txt \
> | perl -0007 -MJSON -nE'say to_json(from_json($_, {allow_nonref=>1}), 
>                                     {pretty=>1})'
{
   "bar" : "ipsum",
   "foo" : "lorem"
}

Note 2: If you run

echo '{ "Düsseldorf": "lorem", "bar": "ipsum" }' \
| python -c'import fileinput, json;
print(json.dumps(json.loads("".join(fileinput.input())),
                 sort_keys=True, indent=4))'

the nicely readable word becomes \u encoded

{
    "D\u00fcsseldorf": "lorem", 
    "bar": "ipsum"
}

If the remainder of your pipeline will gracefully handle unicode and you'd like your JSON to also be human-friendly, simply use ensure_ascii=False

echo '{ "Düsseldorf": "lorem", "bar": "ipsum" }' \
| python -c'import fileinput, json;
print json.dumps(json.loads("".join(fileinput.input())),
                 sort_keys=True, indent=4, ensure_ascii=False)'

and you'll get:

{
    "Düsseldorf": "lorem", 
    "bar": "ipsum"
}

UPDATE I'm using jq now as suggested in another answer. It's extremely powerful at filtering JSON, but, at its most basic, also an awesome way to pretty print JSON for viewing.

jsonpp is a very nice command line JSON pretty printer.

From the README:

Pretty print web service responses like so:

curl -s -L http://<!---->t.co/tYTq5Pu | jsonpp

and make beautiful the files running around on your disk:

jsonpp data/long_malformed.json

If you're on Mac OS X, you can brew install jsonpp. If not, you can simply copy the binary to somewhere in your $PATH.

Try pjson. It has colors!

Install it with pip:

⚡ pip install pjson

And then pipe any JSON content to pjson.

Or, with Ruby:

echo '{ "foo": "lorem", "bar": "ipsum" }' | ruby -r json -e 'jj JSON.parse gets'

You can use this simple command to achieve the result:

echo "{ \"foo\": \"lorem\", \"bar\": \"ipsum\" }"|python -m json.tool

I use jshon to do exactly what you're describing. Just run:

echo $COMPACTED_JSON_TEXT | jshon

You can also pass arguments to transform the JSON data.

Check out Jazor. It's a simple command line JSON parser written in Ruby.

gem install jazor
jazor --help

You only need to use jq

If jq is not installed then you need to install jq first:

sudo apt-get update
sudo apt-get install jq

After installing jq then only need to use jq:

echo '{ "foo": "lorem", "bar": "ipsum" }' | jq

Output looks like

{
  "foo": "lorem",
  "bar": "ipsum"
}

JSONLint has an open-source implementation on GitHub that can be used on the command line or included in a Node.js project.

npm install jsonlint -g

and then

jsonlint -p myfile.json

or

curl -s "http://api.twitter.com/1/users/show/user.json" | jsonlint | less

Simply pipe the output to jq ..

Example:

twurl -H ads-api.twitter.com '.......' | jq .

You can simply use standard tools like jq or json_pp.

echo '{ "foo": "lorem", "bar": "ipsum" }' | json_pp

or

echo '{ "foo": "lorem", "bar": "ipsum" }' | jq

will both prettify output like the following (jq even more colorful):

{
  "foo": "lorem",
  "bar": "ipsum"
}

The huge advantage of jq is that it can do A LOT more if you'd like to parse and process the json.

With Perl, if you install JSON::PP from CPAN you'll get the json_pp command. Stealing the example from B Bycroft you get:

[pdurbin@beamish ~]$ echo '{"foo": "lorem", "bar": "ipsum"}' | json_pp
{
   "bar" : "ipsum",
   "foo" : "lorem"
}

It's worth mentioning that json_pp comes pre-installed with Ubuntu 12.04 (at least) and Debian in /usr/bin/json_pp

Pygmentize

I combine Python's json.tool with pygmentize:

echo '{"foo": "bar"}' | python -m json.tool | pygmentize -g

There are some alternatives to pygmentize which are listed in my this answer.

Here is a live demo:

I recommend using the json_xs command line utility which is included in the JSON::XS perl module. JSON::XS is a Perl module for serializing/deserializing JSON, on a Debian or Ubuntu machine you can install it like this:

sudo apt-get install libjson-xs-perl

It is obviously also available on CPAN.

To use it to format JSON obtained from a URL you can use curl or wget like this:

$ curl -s http://page.that.serves.json.com/json/ | json_xs

or this:

$ wget -q -O - http://page.that.serves.json.com/json/ | json_xs

and to format JSON contained in a file you can do this:

$ json_xs < file-full-of.json

To reformat as YAML, which some people consider to be more humanly-readable than JSON:

$ json_xs -t yaml < file-full-of.json

jj is super-fast, can handle ginormous JSON documents economically, does not mess with valid JSON numbers, and is easy to use, e.g.

jj -p # for reading from STDIN

or

jj -p -i input.json

It is (2018) still quite new so maybe it won’t handle invalid JSON the way you expect, but it is easy to install on major platforms.

bat is a cat clone with syntax highlighting:

Example:

echo '{"bignum":1e1000}' | bat -p -l json

-p will output without headers, and -l will explicitly specify the language.

It has colouring and formatting for JSON and does not have the problems noted in this comment: How can I pretty-print JSON in a shell script?

Install yajl-tools with the command below:

sudo apt-get install yajl-tools

then,

echo '{"foo": "lorem", "bar": "ipsum"}' | json_reformat