FortressFlag

Feature flags · billed per device

Change your app's behaviour without shipping a build

Define a flag, target who should see it, flip it - your apps and your backends pick up the change within about a minute.

Start free trialSee pricing

First 1,000 devices free · no card · no time limit

A working miniature of the FortressFlag dashboard's flags screen. The switches toggle, and dark-mode changes this page's theme.

fortressflag.com/projects/example/flags
Flags
new-checkout
Rolls out the redesigned checkout flow.
dark-mode
Enables the dark theme in your application.
beta-banner
Shows the beta feedback banner.
Propagation
~1 min
Billing unit
1 device
Free tier
1,000
SDKs
7

Capabilities

Everything a flag platform owes you

All of it ships today, none of it is roadmap - and the seven SDKs that serve it span client and server.

Target, then roll outOrdered rules with first-match-wins targeting, reusable segments, and sticky percentage rollouts - nothing about any device's cohort is ever stored.rules · segments · semver
Production, guardedPeer-approved change proposals for production, scheduled toggles that take effect exactly on time, and stale-flag nudges before the cruft sets in.approvals · schedules
Enterprise accessRole-based access, per-project allowlists, SAML SSO with SCIM provisioning, MFA, and an append-only audit log of every change.rbac · sso · scim · mfa
Fail-safe by contractEvery SDK resolves every read to a value: clients cache the last known values durably, servers evaluate in-process from the last ruleset. A FortressFlag outage can never take your app down - that is a contract, not a best effort.offline-first · in-process
Automate itMachine credentials that act as the member who minted them, and an MCP server that hands your AI coding agent the same tools - reading freely, writing deliberately, with production approvals still a person's job.api tokens · mcp

AI agents

Give your coding agent your flags

An MCP server that hands your agent real tools - list, create, toggle - with your role and your project access, never more. A production change always requires a human action outside of the MCP server. Read more in the documentation.

An illustration of an agent session: asked to import existing flags, the agent scans the codebase and creates them in FortressFlag's dev environment.

Try it on your app today

Signing up creates a working organisation with example flags in under a minute. Your first 1,000 monthly-active devices are free, for as long as you like.

Start free trial