jsonlint

jsonlint is a comprehensive JSON validation tool that provides command-line interface for ensuring JSON files conform to specifications and maintain proper structure. It serves as the essential validator for JSON data integrity across web applications, APIs, and configuration systems.

Key Features:

Pure JavaScript Implementation: Native JavaScript JSON parser ensuring accurate validation without external dependencies
Strict JSON Compliance: Validates against official JSON specification to ensure maximum compatibility
Syntax Error Detection: Identifies malformed JSON structures, missing brackets, invalid characters, and formatting issues
Fast Validation: High-performance parsing suitable for large JSON files and batch processing
Detailed Error Reporting: Clear error messages with line and column information for easy debugging
Configurable Options: Flexible validation options through .jsonlintrc configuration files
Batch Processing: Efficient validation of multiple JSON files in a single command
Cross-Platform: Consistent validation behavior across Windows, macOS, and Linux environments

jsonlint documentation

Version in MegaLinter: 16.0.0
Visit Official Web Site
See How to configure jsonlint rules
See Index of problems detected by jsonlint

Configuration in MegaLinter

Enable jsonlint by adding JSON_JSONLINT in ENABLE_LINTERS variable
Disable jsonlint by adding JSON_JSONLINT in DISABLE_LINTERS variable

Variable	Description	Default value
JSON_JSONLINT_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
JSON_JSONLINT_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: `-s --foo "bar"`
JSON_JSONLINT_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: `(src\\|lib)`	Include every file
JSON_JSONLINT_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: `(test\\|examples)`	Exclude no file
JSON_JSONLINT_CLI_LINT_MODE	Override default CLI lint mode - `file`: Calls the linter for each file - `list_of_files`: Call the linter with the list of files as argument - `project`: Call the linter from the root of the project	`list_of_files`
JSON_JSONLINT_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".json"]`
JSON_JSONLINT_FILE_NAMES_REGEX	File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files Ex: `["Dockerfile(-.+)?", "Jenkinsfile"]`	Include every file
JSON_JSONLINT_PRE_COMMANDS	List of bash commands to run before the linter	None
JSON_JSONLINT_POST_COMMANDS	List of bash commands to run after the linter	None
JSON_JSONLINT_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling JSON_JSONLINT and its pre/post commands	None
JSON_JSONLINT_CONFIG_FILE	jsonlint configuration file nameUse `LINTER_DEFAULT` to let the linter find it	`.jsonlintrc`
JSON_JSONLINT_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
JSON_JSONLINT_DISABLE_ERRORS	Run linter but consider errors as warnings	`false`
JSON_JSONLINT_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
JSON_JSONLINT_CLI_EXECUTABLE	Override CLI executable	`['jsonlint']`

MegaLinter Flavors

This linter is available in the following flavors

Flavor	Description	Embedded linters
all	Default MegaLinter Flavor	127
c_cpp	Optimized for pure C/C++ projects	57
ci_light	Optimized for CI items (Dockerfile, Jenkinsfile, JSON/YAML schemas,XML	22
cupcake	MegaLinter for the most commonly used languages	88
documentation	MegaLinter for documentation projects	50
dotnet	Optimized for C, C++, C# or VB based projects	65
dotnetweb	Optimized for C, C++, C# or VB based projects with JS/TS	74
go	Optimized for GO based projects	52
java	Optimized for JAVA based projects	55
javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	60
php	Optimized for PHP based projects	55
python	Optimized for PYTHON based projects	66
ruby	Optimized for RUBY based projects	51
rust	Optimized for RUST based projects	51
salesforce	Optimized for Salesforce based projects	55
swift	Optimized for SWIFT based projects	51
terraform	Optimized for TERRAFORM based projects	55

Behind the scenes

How are identified applicable files

File extensions: .json

How the linting is performed

jsonlint is called once with the list of files as arguments (list_of_files CLI lint mode)

Example calls

jsonlint myfile1.json myfile2.json

Help content

JSON/CJSON/JSON5 parser, syntax and schema validator and pretty-printer.

Usage: jsonlint [options] [--] [<file, directory, pattern> ...]

Options:
  -f, --config <file>          read options from a custom configuration file
  -F, --no-config              disable searching for configuration files
  --ignore-proto-key           ignore occurrences of "__proto__" object key
  --ignore-prototype-keys      ignore all keys from "Object.prototype"
  -s, --sort-keys              sort object keys (not when prettifying)
  --sort-keys-ignore-case      sort object keys ignoring the letter case
  --sort-keys-locale <id>      locale identifier to sort object keys with
                               (or "default" for the system default)
  --sort-keys-case-first <id>  order if only letter case is different
                               ("upper", "lower" and "false" are allowed)
  --sort-keys-numeric          sort by numbers recognised in object keys
  -E, --extensions <ext...>    file extensions to process for directory walk
                               (default: json, JSON)
  -i, --in-place               overwrite the input files
  -j, --diff                   print difference instead of writing the output
  -k, --check                  check that the input is equal to the output
  -t, --indent <num|char>      number of spaces or specific characters to use
                               for indentation or a string with whitespace
  -c, --compact                compact error display
  -M, --mode <mode>            set other parsing flags according to the format
                               of the input data (default: json)
  -B, --bom                    ignore the leading UTF-8 byte-order mark
  -C, --comments               recognize and ignore JavaScript-style comments
  -S, --single-quoted-strings  support single quotes as string delimiters
  -T, --trailing-commas        ignore trailing commas in objects and arrays
  -D, --no-duplicate-keys      report duplicate object keys as an error
  -V, --validate <file...>     JSON Schema file(s) to use for validation
  -e, --environment <env>      which version of JSON Schema the validation
                               should use
  -x, --context <num>          line number used as the diff context
                               (default: 3)
  -l, --log-files              print only the parsed file names to stdout
  -q, --quiet                  do not print the parsed json to stdout
  -n, --continue               continue with other files if an error occurs
  -p, --pretty-print           prettify the input instead of stringifying
                               the parsed object
  -P, --pretty-print-invalid   force pretty-printing even for invalid input
  -r, --trailing-newline       ensure a line break at the end of the output
  -R, --no-trailing-newline    ensure no line break at the end of the output
  --prune-comments             omit comments from the prettified output
  --strip-object-keys          strip quotes from object keys if possible
  --enforce-double-quotes      surrounds all strings with double quotes
  --enforce-single-quotes      surrounds all strings with single quotes
  --trim-trailing-commas       omit trailing commas from objects and arrays
  --succeed-with-no-files      succeed (exit code 0) if no files were found
  -v, --version                output the version number
  -h, --help                   display help for command

Examples:
  $ jsonlint myfile.json
  $ jsonlint --in-place --pretty-print mydir
  $ jsonlint --comments --trailing-commas --no-duplicate-keys \
      --log-files --compact --continue '**/*.json' '!**/node_modules'

Installation on mega-linter Docker image

Dockerfile commands :

# renovate: datasource=npm depName=@prantlf/jsonlint
ARG NPM_PRANTLF_JSONLINT_VERSION=16.0.0

NPM packages (node.js):
- @prantlf/jsonlint@16.0.0