In one sentence
Charges for keeping shipping containers past their free time, inside the terminal (demurrage) or outside it (detention).
Demurrage and detention are fees that carriers and terminals charge when a shipping container is kept beyond the free time allowed. Terms differ by carrier, port and contract, but in common US usage demurrage applies while a loaded container stays at the terminal past its free days, and detention applies when a container is kept outside the terminal, at a warehouse or on a chassis, past the free days for returning it. Some contracts combine the two into one charge.
Why the charges add up
Daily rates often rise the longer a container is kept, and a shipment can carry several containers. Missed pickup windows, late customs release, holds, appointment shortages and slow paperwork are common causes. Many of these are visible days in advance in carrier and terminal data, but the warning sits in an email or portal nobody checks in time.
Rules on billing
In the United States the Federal Maritime Commission issued a final rule in 2024 on demurrage and detention billing requirements, which sets what must appear on an invoice, sets billing timeframes and gives billed parties at least 30 calendar days to ask for mitigation, refund or waiver. The FMC reports that nine ocean carriers collected roughly $15.4 billion in these charges from April 2020 through March 2025.
What automation does:
Free time tracking
Pull last free day and empty return dates from carrier and terminal data for every container and show them in one list.
Early alerts
Warn the right person a set number of days before free time runs out, with the reason the container has not moved.
Exception handling
Flag holds, customs issues and missed appointments as soon as they appear.
Invoice checks
Compare carrier invoices to tracked dates and flag charges that do not match, so disputes are raised within the allowed time.
In our builds
for freight forwarders the free time list is the first thing we automate, because it turns a charge found after the fact into an alert with time to act.
Keep following the system
Workflow Automation
Connecting business systems so repeatable tasks run according to defined rules and exceptions reach the right person.
API Integration
A connection that lets software systems exchange approved data and invoke supported operations.
Webhook
An HTTP message one system sends to another the moment an event happens, so the receiver does not have to keep asking.
OpenClaw
An open-source, self-hosted Gateway for a personal AI assistant that connects models, tools, sessions and messaging channels.
Hermes Agent
An open-source, single-tenant personal AI agent from Nous Research that works from a terminal and chat channels.
Buzz (Block)
An open-source, self-hostable team workspace from Block where people and AI agents share rooms on a signed Nostr event log.