jq . file.json

is what I was looking for. I didn't realize that the . is a filter and not a placeholder for the piped in content:

.

The absolute simplest (and least interesting) filter is .. This is a filter that takes its input and produces it unchanged as output.

And the man page makes it clear that the filter is a required argument.

I did find a solution while I was writing the question: don't put the input inside string interpolation, output a stream of things:

echo '{"foo":"bar", "baz":[1,2,3]}' | jq -r '"My value is:", . , "Some other stuff"'
# .........................................................^^^^^

outputs

My value is:
{
  "foo": "bar",
  "baz": [
    1,
    2,
    3
  ]
}
Some other stuff

While it is probably best to use a tool like the one peak suggested if your json isn't too complex you could use a second jq invocation to postprocess the output of the first. For example if your data is in data.json

$ jq -M . data.json | jq -MRsr 'gsub("\n      +";"")|gsub("\n    ]";"]")'

produces

{
  "frameGrid": {
    "size": [24,24],
    "dimensions": [1,1],
    "names": [["default"]]
  }
}

You need to supply a filter as an argument. To pass the JSON through unmodified other than the pretty printing jq provides by default, use the identity filter .:

curl -s https://api.github.com/users/octocat/repos | jq '.' | cat

With Python 2.6+ or 3 you can use the json.tool module:

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.

Another useful option might be --no-ensure-ascii which disables escaping of non-ASCII characters (new in version 3.9).

Ok tried to understand your problem exactly... This is what is happening:

$ echo '{"value": "New", "onclick": "CreateNewDoc()"}' | jq | grep value
jq - commandline JSON processor [version 1.5-1-a5b5cbe]
Usage: jq [options] <jq filter> [file...]
[rest of output is omitted for brevity]

The important thing to notice here is the usage line (emphasis is mine):

Usage: jq [options] <jq filter> [file...]

The filter is not optional, if you don't give one, jq tries to parse the rest of the command line as its filter and throws an error. A workaround for your case here is:

$ echo '{"value": "New", "onclick": "CreateNewDoc()"}' | jq '.' | grep value
  "value": "New",

which indeed greps the "value" line as the filter passed is '.' - this just pretty prints the json content, but that's far from the best use of jq. If you wish to get only this line it would be better do:

$ echo '{"value": "New", "onclick": "CreateNewDoc()"}' | jq '.value'
"New"

If you wish to get the output without quotes then you can add add -r option to jq like so:

$ echo '{"value": "New", "onclick": "CreateNewDoc()"}' | jq -r '.value'
New

from jq --help:

-r output raw strings, not JSON texts;

that's a little introduction to jq, that's probably not enough to solve your problem at all but as you didn't specify your problem I can't help more than that.