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Introduction

What is Limiter?​

Limiter is an open source, privacy-friendly Plan and Feature management solution for your SaaS products.

Why use Limiter?​

Limiter helps you bridge the gap between formulating a pricing model and actually implementing it.

It provides an opinionated framework to handle the things that you would normally have to write (a lot more) code for:

  • Keep track of the plans and the features that they contain.
  • Keep track of which users belong to which plans, and by extension, whether they are entitled to a particular feature.
  • Support multiple feature types, ranging from basic toggles, to limits and quotas.
  • Track usage of a feature, determine whether a user has exceeded any limits set.
  • Hook into your payment provider's subscription lifecycle and assign users to the correct plans.
  • Provide a single pane of glass where you can view usage insights of all features, across plans.

Core Concepts​

These terms are used widely within the Limiter docs, and here's our interpretation of them.

Plan Management​

Plan management is the ability to create plans and curate the features that go into these plans. Features can be reused across plans or be specific to a particular plan. This grants you the flexibility to implement various types of pricing models from tier-based plans to bespoke plans for enterprise use-cases.

Entitlement​

An entitlement refers to the right to use a feature. In the context of a plan-based SaaS app, it is essentially whether Bob on Plan A can use Feature X.

In Limiter, users are bound to plans and plans contain features. By transitive property, it determines whether a user is entitled to a feature via said plan.

Usage Limit​

In some cases, a feature may be more than simply being enabled or disabled in a given plan. You may want to impose a limit on the number of times a user can use a particular feature. For example, capping the number of workspaces you can create in a project management tool.

Quota​

A quota is a usage limit is periodically reset. A common use-case is to limit the daily usage of an expensive API call.

Feature Flag​

A feature flag in is simplest form, is an if-else statement, gating the execution of a freshly written block of code. Limiter builds on top of this foundation to allow a feature flag to be used for entitlements, usage limits and quotas.

Project​

A project is a logical grouping of plans. Typically, one SaaS is a project. Although you can also use multiple projects per SaaS to cater for different environments eg. development, staging, production.

Plan​

A plan is a logical grouping of features. Each plan should map to a subscription plan that you have set up on your payments provider. Your users should be bound to plans once they have paid for a subscription (or bound to a 'Free' plan by default).

Feature​

A feature is essentially a feature flag on steriods. It is stateful and can contain metadata as well as keep track of usage on a per user basis.

Feature Matrix​

The feature matrix is a json document that contains a mapping of plans to features for a project.

Feature Usage​

The feature usage is a json document that contains a mapping of features to usage counts for a user.

Note that Limiter stores a flat map of features to usage counts. The exact same feature name could be used in multiple plans and we would still increment / decrement the same counter. This is because a user is expected to be in one and only one plan at any point in time.