What are people using it for? Creating the product PoC or demo before even starting out with the backend REST, GraphQL, and other APIs mocking and testing Hiding critical enterprise infrastructure behind a simple static facade Hacking and fine-tuning HTTP communications on both server and client sides

Get started | Usage | Usage Examples | How does it work? | Features | Optional Headers | CLI | Cheatsheet

Get started

1. Download the latest release of df.jar
2. Copy-paste the content of the dump example to the file dump.txt:

   GET /api/customer/123 HTTP/1.1
   
   HTTP/1.1 200 OK
   Content-Type: application/json
   
   {
       "id": 123,
       "fname": "John",
       "lname": "Doe",
       "email": ["john@example.com", "johndoe@example.com"]
   }
   

3. Start the server from command line:

   java -jar df.jar --dump dump.txt
   

4. Use a browser to check whether the server is running:
   

   http://localhost:8080/api/customer/123

5. Get response:
   

That's it!

For more examples see the cheatsheet.
Also take look at REST version of the Spring PetClinic built with DeepfakeHTTP.

Usage

java -jar df.jar [OPTIONS] [FLAGS] [COMMANDS]                                 
                                                                              
OPTIONS:                                                                       
   --host <host>            host name, default: localhost                      
   --port <number>          HTTP TCP port number, default: 8080                
   --port-ssl <number>      HTTPS TCP port number, default: 8443               
   --dump <file|url>...     dump text file(s)/URL(s)
   --db <file|url>          json/yaml/csv memory file to populate templates    
   --db-export <file>       export memory to json file                         
   --db-path <path>         serve live memory file at specified context        
   --dir <dir>              forward unmatched requests to specified directory            
   --js <file|url>...       JavaScript file(s) for script engine context       
   --openapi-path <path>    serve built-in OpenAPI client at specified context 
   --openapi-title <text>   provide custom OpenAPI specification title         
   --collect <file>         collect live request/response to file              
   --format <json|yaml>     output format for --print-* commands, default: json
   --status <number>        status code for non-matching requests, default: 404
   --max-log-body <number>  max body bytes in console log, default: unlimited  
                                                                               
FLAGS:                                                                         
   --no-log                 disable request/response console logging           
   --no-log-request-info    disable request info in console logging            
   --no-log-headers         disable request/response headers in console logging
   --no-log-body            disable request/response body in console logging   
   --no-cors                disable CORS headers                               
   --no-etag                disable 'ETag' header                              
   --no-server              disable 'Server' header                            
   --no-watch               disable watch files for changes                    
   --no-color               disable ANSI color output for --print-* commands   
   --no-pretty              disable prettyprint for --print-* commands         
   --no-template            disable template processing                        
   --no-wildcard            disable wildcard processing                        
   --no-bak                 disable backup old memory file before overwrite    
   --strict-json            enable strict JSON comparison                      
   --redirect               enable redirect HTTP to HTTPS                      
   --db-export-on-exit      export memory only on server close event           
                                                                               
COMMANDS:                                                                      
   --help                   print help message                                 
   --print-info             print dump files statistics to stdout as json/yaml 
   --print-requests         print dump requests to stdout as json/yaml         
   --print-openapi          print OpenAPI specification to stdout as json/yaml

Usage Examples

Start server on dump file:

java -jar df.jar --dump dump.txt

Start server with built-in OpenAPI client:

java -jar df.jar --openapi-path /api --dump dump.txt

more examples…

Start server on few dump files:

java -jar df.jar --dump dump1.txt dump2.txt dump3.txt

Start server with built-in OpenAPI client with custom title:

java -jar df.jar --openapi-path /api --openapi-title 'My REST API v18.2.1' --dump dump.txt

even more examples…

Collect live request/response to file:

java -jar df.jar --collect /home/john/live.txt --dump dump.txt

Specify JSON data file to populate templates:

java -jar df.jar --data /home/john/data.json --dump dump.txt

Print dump files statistics to stdout as JSON:

java -jar df.jar --print-info --dump dump.txt

Print dump requests to stdout as JSON:

java -jar df.jar --print-requests --dump dump.txt

Print OpenAPI specification to stdout as JSON:

java -jar df.jar --print-openapi --dump dump.txt

If you still need examples make sure to check out the cheatsheet.

Prerequisites

• Java 15 or above

How does it work?

1. Got the client's request.
2. Search the dump for corresponded entry (request-response pair) by matching all specified request's parts:
   method, URI, headers, and body.
3. If the entry was found, the server sends the appropriate response to the client.
4. If the entry was not found, the server sends a status 404.

That's all.

Features

    ✓  no dependencies
    ✓  no installation
    ✓  no configs
    ✓  crossplatform
    ✓  single-file executable
    ✓  command-line interface

more features…

    ✓  fully asynchronous
    ✓  HTTP message formats RFC 7230
    ✓  multiple entries per dump
    ✓  multiple request/response entries per dump
    ✓  extracts responses from HTTP dumps
    ✓  self-hosted built-in OpenAPI client
    ✓  exportable persistent memory
    ✓  persistent data
    ✓  CGI, XGI and JavaScript handlers
    ✓  GET, HEAD, POST, PUT, DELETE etc.
    ✓  multi-line and multi-value headers RFC 7230
    ✓  openAPI-styled templates in paths
    ✓  wildcards ( * and ? with escape / ) in query string and header values
    ✓  templates in URI, headers, body
    ✓  body fetching from external sources like URLs, local files, and data URI
    ✓  per entry user-defined request/response delays
    ✓  comments # in dumps
    ✓  live request/response collection
    ✓  watching dump files for changes
    ✓  ETag support
    ✓  CORS support
    ✓  live request/response logging
    ✓  TLS(SSL) connections and HTTP to HTTPS redirect
    ✓  customizable OpenAPI client path
    ✓  latest OpenAPI specification v3.0.3 support
    ✓  colorized console output
    ✓  disabling color via command line or NO_COLOR environment variable

LICENSE

The DeepfakeHTTP is released under the MIT license.

APPENDIX A.
Command line options

Option	Default	Description
--host <host name>	localhost	host name, default: localhost See Also:        --port <number>        --port-ssl <number>        --redirect
--port <number>	8080	HTTP TCP port number, default: 8080 See Also:        --port-ssl <number>        --redirect        --host <host name>
--port-ssl <number>	8443	HTTPS TCP port number, default: 8443 Create TLS(SSL) connection based on built-in self-signed certificate See Also:        --port <number>        --redirect        --host <host name>
--dump <file|url>...		Dump text file(s)/URL(s)
--db <file|url>...		JSON/YAML/CSV memory file to populate templates See Also:        --db-export <file>        --db-path <path>        --no-bak        --js <file|url>...        X-Handler-JS
--db-export <file>		Export memory to JSON file See Also:        --db <file|url>...        --db-path <path>        --no-bak
--db-path <path>		Serve live memory file at specified context. With this option you can view or export the memory state in JSON format. See Also:        --db <file|url>...        --db-export <file>        --no-bak
--dir <dir>		Forward unmatched requests to specified directory. See Also:        --dump <file|url>...
--js <file|url>...		JavaScript file(s) for script engine context. See Also:        X-Handler-JS        --db <file|url>...
--openapi-path <path>		Serve built-in OpenAPI client at specified context See Also:        --openapi-title <text>        --print-openapi        X-OpenAPI-Summary        X-OpenAPI-Description        X-OpenAPI-Tags        X-OpenAPI-Parameters
--openapi-title <text>		Provide custom OpenAPI specification title See Also:        --openapi-path <path>        --print-openapi        X-OpenAPI-Summary        X-OpenAPI-Description        X-OpenAPI-Tags        X-OpenAPI-Parameters
--collect <file>		Collect live request/response to file
--format <json|yaml>	json	Output format for --print-* commands, default: json
--status <number>	404	Status code for non-matching requests, default: 404
--max-log-body <number>		Max body bytes in console log, default: unlimited See Also:        --no-log        --no-log-body        --no-log-headers
--no-log		Disable request/response console logging See Also:        --no-log-request-info        --no-log-body        --max-log-body <number>        --no-log-headers
--no-log-request-info		Disable request info in console logging See Also:        --no-log        --no-log-body        --max-log-body <number>        --no-log-headers
--no-log-headers		Disable request/response headers in console logging See Also:        --no-log        --no-log-request-info        --no-log-body        --max-log-body <number>
--no-log-body		Disable request/response body in console logging See Also:        --max-log-body <number>        --no-log        --no-log-request-info        --no-log-headers
--no-cors		Disable CORS headers
--no-etag		Disable ETag header
--no-server		Disable Server header
--no-watch		Disable watch files for changes
--no-color		Disable ANSI color output for --print-* commands ANSI color output also can be disabled via NO_COLOR environment variable. See Also:        --no-pretty
--no-pretty		Disable prettyprint for --print-* commands See Also:        --no-color
--no-template		Disable template processing
--no-wildcard		Disable wildcard processing. By default wildcard processing is enabled. The asterisk * represents one or more characters, the question mark ? represents a single character, and / represents escape character.
--no-bak		Disable backup old memory file before overwrite. The memory file is overwritten every time the server shuts down. See Also:        --db <file|url>...        --db-export <file>        --db-path <path>
--strict-json		Enable strict (byte by byte) JSON comparison
--redirect		Enable redirect HTTP to HTTPS See Also:        --port <number>        --port-ssl <number>        --host <host name>
--help		Print help message
--print-info		Print dump files statistics to stdout as json/yaml See Also:        --format <json|yaml>        --no-color        --no-pretty
--print-requests		Print dump requests to stdout as json/yaml See Also:        --format <json|yaml>        --no-color        --no-pretty
--print-openapi		Print OpenAPI specification to stdout as json/yaml See Also:        --openapi-path <path>        --openapi-title <text>        --format <json|yaml>        --no-color        --no-pretty

APPENDIX B.
Optional REQUEST / RESPONSE headers

Header	Description
X-Delay	Request or response delay (in milliseconds). Examples: Two seconds request delay: GET / HTTP/1.1 X-Delay: 2000 Two seconds response delay: HTTP/1.1 200 OK X-Delay: 2000
X-Content-Source	The URL of the externally hosted content. The content from the URL will be sent as the response body. Supported protocols: http:, https:, file:, data:. If the URL provides its own content type and there is no Content-Type header in the dump, the original Content-Type header received from the URL will be sent along with other response headers. This header is useful when you want to send content hosted on a remote server or just send binary data as a response body. Examples: Get a response body from a remote server: HTTP/1.1 200 OK Content-Type: application/json X-Content-Source: http://example.com/api/car/1234.json Get a response body from a file: HTTP/1.1 200 OK Content-Type: image/jpeg X-Content-Source: file:///home/john/photo.jpeg Get a response body from a data URI: HTTP/1.1 200 OK Content-Type: image/gif X-Content-Source: data:image/gif;base64,R0lGODlhAQABAIAAAP...
X-OpenAPI-Summary	OpenAPI request summary text. Example: GET /api/customer{id} HTTP/1.1 X-OpenAPI-Summary: Get customer information See Also:        X-OpenAPI-Description        X-OpenAPI-Tags        X-OpenAPI-Parameters
X-OpenAPI-Description	OpenAPI request description text. Example: GET /api/customer{id} HTTP/1.1 X-OpenAPI-Summary: Get customer information X-OpenAPI-Description: This API extracts customer info from db See Also:        X-OpenAPI-Summary        X-OpenAPI-Tags        X-OpenAPI-Parameters
X-OpenAPI-Tags	OpenAPI request comma-separated tag list. Example: GET /api/customer{id} HTTP/1.1 X-OpenAPI-Summary: Get customer information X-OpenAPI-Description: This API extracts customer info from db X-OpenAPI-Tags: Work with customer, Buyers, Login info See Also:        X-OpenAPI-Summary        X-OpenAPI-Description        X-OpenAPI-Parameters
X-OpenAPI-Parameters	OpenAPI request parameters information. Example: GET /api/customer{id} HTTP/1.1 X-OpenAPI-Summary: Get customer information X-OpenAPI-Description: This API extracts customer info from db X-OpenAPI-Tags: Work with customer, Buyers, Login info X-OpenAPI-Parameters: name=cust_id;description=Customer ID, name=rdate;description=Review Date See Also:        X-OpenAPI-Summary        X-OpenAPI-Description        X-OpenAPI-Tags
X-Forward-To	Forward client request to specified origin. Acts as a forward proxy. Example: HTTP/1.1 X-Forward-To: http://example.com:8080
X-Handler-CGI	CGI (Common Gateway Interface) program. Example: HTTP/1.1 200 OK X-Handler-CGI: /home/john/myprog.sh param1 param2 See Also:        X-Handler-XGI        X-Handler-JS
X-Handler-XGI	XGI (Extended Gateway Interface) program. XGI program is very similar to CGI, but unlike CGI, the XGI program reads from stdin not only the body of the request but also the first line and the headers. In response XGI program writes status line, headers and response body into stdout. All CGI environment variables are also available to XGI program. Example: HTTP/1.1 X-XGI: /home/john/myprog.sh param1 param2 See Also:        X-Handler-CGI        X-Handler-JS
X-Handler-JS	JavaScript response handler function. The JavaScript functions are taken from the context files listed in the --js <file|url>... option. The following objects are provided as handler function parameters: request - object, READ ONLY request.method: string E.g. request.method ➞ post request.path: string E.g. request.path ➞ /api/customers request.query: string E.g. request.query ➞ fname=John&lname=Doe request.parameters: object E.g. request.parameters.fname[0] ➞ John headers: object E.g. request.headers['content-type'][0] ➞ application/json request.body: string | object E.g. request.body ➞ {"fname": "Jonh", lname: "Doe"} response - object, READ | WRITE response.status: number E.g. response.status = 200 response.headers: object E.g. response.headers['Content-Type'] = 'application/json' response.body: string | object E.g. response.body = {"fname": "Jonh", lname: "Doe"} data: object, READ | WRITE - persistent user data from the file provided by --db option Among other things, the X-Handler-JS header allows you to modify persistent data. Examples: JavaScript function modify memory data: DELETE /customers/{id} HTTP/1.1 200 OK X-Handler-JS: deleteCustomer Content-Type: application/json {"id": "${request.parameters.id[0]}"}; function deleteCustomer(request, response, data) { const id = request.parameters.id[0]; delete data.customers[id]; } JavaScript function modify memory data and provide response status, headers and body: DELETE /customers/{id} HTTP/1.1 X-Handler-JS: deleteCustomer function deleteCustomer(request, response, data) { const id = request.parameters.id[0]; if (data.customers[id] === undefined) { response.status = 404; response.body = {error: true, message: 'ID not found'}; } delete data.customers[id]; response.status = 200; response.headers['Content-Type'] = 'application/json'; response.body = {error: false, message: null}; } See Also:        --js <file|url>...        --db <file|url>...        X-Handler-CGI        X-Handler-XGI

NOTE:
            1. Optional request headers will not be sent to the server engine.
            2. Optional response headers will not be sent to clients.