Pricing4APIs: A Rigorous Model for RESTful API Pricings

TL;DR

This paper introduces a comprehensive model for API pricing plans, extending industry standards to enable precise description, validation, and analysis of API pricing structures, supported by real-world data and tools.

Contribution

It proposes the first rigorous API pricing model and serialization extension for OpenAPI, along with validation tools and an empirical analysis of real-world APIs.

Findings

Validated the expressiveness of the model on 268 APIs

Created a dataset of 54 pricing models for testing

Developed tools for automated validation of API pricing descriptions

Abstract

APIs are increasingly becoming new business assets for organizations and consequently, API functionality and its pricing should be precisely defined for customers. Pricing is typically composed by different plans that specify a range of limitations, e.g., a Free plan allows 100 monthly requests while a Gold plan has 10000 requests per month. In this context, the OpenAPI Specification (OAS) has emerged to model the functional part of an API, becoming a de facto industry standard and boosting a rich ecosystem of vendor-neutral tools to assist API providers and consumers. In contrast, there is no proposal for modeling API pricings (i.e. their plans and limitations) and this lack hinders the creation of tools that can leverage this information. To deal with this gap, this paper presents a pricing modeling framework that includes: (a) Pricing4APIs model, a comprehensive and rigorous model of API pricings, along SLA4OAI, a serialization that extends OAS; (b) an operation to validate the description of API pricings, with a toolset (sla4oai-analyzer) that has been developed to automate this operation. Additionally, we analyzed 268 real-world APIs to assess the expressiveness of our proposal and created a representative dataset of 54 pricing models to validate our framework.