7. OpenAPI Specification

The API is described by a machine-readable specification in OpenAPI 3.1 format. The full JSON schema is published at https://doc.payneteasy.com/openapi.json.

You can use it to:

browse the API interactively in your browser
generate client SDKs in your language of choice
import the API into tools such as Postman or Insomnia
feed it to AI coding assistants to generate clients and integrations

7.1. Response Format

By default the gateway returns responses in application/x-www-form-urlencoded format — the same as it always has. This behaviour is unchanged: when you send no special Accept header, you keep receiving form-encoded responses exactly as before.

To receive the same data as JSON instead, send the Accept: application/vnd.pay+json request header. A JSON response is easier to deserialize, especially when you parse the response by hand.

This affects the response only — the request body is still sent as application/x-www-form-urlencoded in both cases, with or without the header.

Default response (application/x-www-form-urlencoded):

type=async-response
&serial-number=00000000-0000-0000-0000-000002d9b22a
&merchant-order-id=inv4097763
&paynet-order-id=6768788
&end-point-id=22903

The same response when the request includes Accept: application/vnd.pay+json:

{
    "type": "async-response",
    "serial-number": "00000000-0000-0000-0000-000002d9b22a",
    "merchant-order-id": "inv4097763",
    "paynet-order-id": "6768788",
    "end-point-id": "22903"
}

7.2. Interactive Documentation

The full API reference is available online as interactive OpenAPI documentation — no tools or downloads required. Open it in your browser to browse every endpoint, review request and response parameters and data schemas, and send test requests right from the page:

OpenAPI Interactive Documentation

7.3. SDK generation

OpenAPI Generator is a free, open-source tool that reads an OpenAPI specification and generates ready-to-use client SDKs, server stubs, and documentation for more than 50 languages. Its command-line interface, openapi-generator-cli, is the quickest way to turn the specification above into a working client.

Install it using any of the methods below (see the installation guide for all the options):

npm install @openapitools/openapi-generator-cli -g

brew install openapi-generator

docker pull openapitools/openapi-generator-cli

# requires Java 11+; replace <version> with the latest release from
# https://github.com/OpenAPITools/openapi-generator/releases
wget https://repo1.maven.org/maven2/org/openapitools/openapi-generator-cli/<version>/openapi-generator-cli-<version>.jar \
    -O openapi-generator-cli.jar
java -jar openapi-generator-cli.jar version

Then generate a client in the language of your choice:

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g java \
    -o sdk-java

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g python \
    -o sdk-python

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g typescript-fetch \
    -o sdk-ts

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g php \
    -o sdk-php

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g csharp \
    -o sdk-csharp

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g go \
    -o sdk-go

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g ruby \
    -o sdk-ruby

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g kotlin \
    -o sdk-kotlin

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g swift5 \
    -o sdk-swift

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g rust \
    -o sdk-rust

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g dart \
    -o sdk-dart

openapi-generator-cli generate \
    -i https://doc.payneteasy.com/openapi.json \
    -g cpp-restsdk \
    -o sdk-cpp

7.4. Using AI Agents

AI coding assistants — such as Claude Code, ChatGPT, Cursor, and Windsurf — can read an OpenAPI specification and generate a client or integration automatically.

Copy the prompt below into your AI assistant and adjust the target language and requirements as needed:

Generate an API client from this OpenAPI specification:

https://doc.payneteasy.com/openapi.json

Requirements:
- target language: Python (or TypeScript, PHP, Java, ...)
- create a typed API client class
- generate request and response models
- include usage examples