Charges

A Charge is a price component attached to a plan. Plans can have multiple charges — for example, a base subscription fee plus per-unit charges for multiple usage meters.

Charge Types

Type	Description
`FIXED`	A flat amount billed each billing period
`USAGE`	A per-unit price, calculated from metered usage

Creating a Fixed Charge

curl -X POST https://api.fluxrate.co/api/v1/plans/<plan_id>/charges \
  -H "Content-Type: application/json" \
  -H "Cookie: access_token=<token>" \
  -d '{
    "type": "FIXED",
    "unit_price": 99.00,
    "display_name": "Pro monthly subscription"
  }'

Creating a Usage Charge

curl -X POST https://api.fluxrate.co/api/v1/plans/<plan_id>/charges \
  -H "Content-Type: application/json" \
  -H "Cookie: access_token=<token>" \
  -d '{
    "type": "USAGE",
    "meter_id": "<meter_id>",
    "unit_price": 0.005,
    "display_name": "Storage (per GB)"
  }'

Charge Fields

Field	Required	Description
`type`	✅	`FIXED` or `USAGE`
`unit_price`	✅	Price per unit (for USAGE) or flat amount (for FIXED)
`meter_id`	Required for USAGE	The meter whose events are aggregated for billing
`display_name`		How the charge appears on invoices

Managing Charges

View Plan Charges

GET /api/v1/plans/<plan_id>

The response includes a charges array with all active charges.

Deactivate a Charge

curl -X PATCH https://api.fluxrate.co/api/v1/plans/<plan_id>/charges/<charge_id> \
  -H "Content-Type: application/json" \
  -H "Cookie: access_token=<token>" \
  -d '{
    "status": "INACTIVE"
  }'

Charge deactivation is permanent. An inactive charge cannot be reactivated. Create a new charge to replace it.Status can only transition from ACTIVE → INACTIVE.

How Usage Charges are Calculated

At invoice generation time, Fluxrate:

Finds all UsageEvent records for the linked meter within the billing period
Applies the meter’s aggregation type (SUM, MAX, UNIQUE_COUNT, LAST)
Multiplies the result by unit_price
Creates a line item on the invoice

Usage = aggregate(events in period, aggregation_type)
Line Item Total = Usage × unit_price

Multiple Charges on One Plan

Plans can have multiple charges of any type:

Enterprise Plan
├── Base Fee (FIXED) → $500/month
├── API Calls (USAGE) → $0.0005/call
├── Storage (USAGE) → $0.02/GB
└── Premium Support (FIXED) → $100/month

Each charge generates a separate line item on the invoice, giving customers full transparency into what they’re being billed for.

Get Started

Product Guide

Developer Guides

Charge Types

Creating a Fixed Charge

Creating a Usage Charge

Charge Fields

Managing Charges

View Plan Charges

Deactivate a Charge

How Usage Charges are Calculated

Multiple Charges on One Plan

​Charge Types

​Creating a Fixed Charge

​Creating a Usage Charge

​Charge Fields

​Managing Charges

​View Plan Charges

​Deactivate a Charge

​How Usage Charges are Calculated

​Multiple Charges on One Plan

Charge Types

Creating a Fixed Charge

Creating a Usage Charge

Charge Fields

Managing Charges

View Plan Charges

Deactivate a Charge

How Usage Charges are Calculated

Multiple Charges on One Plan