Say it like this
- Put it behind a feature flag
- Toggle the feature flag on and off
- We're running an A/B test with a feature flag
- Feature flag it for now
Use it at work
Releasing
- The feature is behind a feature flag, so it's safe to merge.
- Let's turn on the flag for 10% of users.
During an incident
- Turn off the feature flag. The new checkout is failing.
- We disabled the flag and errors stopped.
Cleaning up
- Please remove old feature flags after launch.
- We have over 200 flags. Let's clean up.
Don't say this
Feature flags are for controlling feature visibility, not for deploying bug fixes. Bug fixes are typically deployed directly.
Don't mix it up
| Term | What it is | Who writes or uses it | When |
|---|---|---|---|
| feature flag | Switch to turn a feature on or off | Developers | Releases and tests |
| feature branch | Branch for one feature | Developers | During development |
| config | App settings | Developers | Any setting |
Practice
Try it
4 quick exercises
1. Your team deployed code that might cause issues. How do you describe it?
2. We need to _______ the new search algorithm before it reaches all users.
3. Which sentence uses feature flag correctly?
4. Rewrite using feature flag: 'We want to put the new feature into production but only show it to some customers while we check for problems.'
Say it out loud
Phrase 1 of 4
"Put it behind a feature flag"
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More about feature flag
Real examples(4)
- in a standup
"We merged the new dashboard code this morning, but we feature flagged it so only internal users can see it right now."
- in a code review
"Good catch—wrap this API change in a feature flag so we can deploy safely without breaking existing clients."
- in a team meeting
"The feature flag lets us gradually roll out the redesign to 10 percent of users on Monday and scale up if there are no issues."
- in a Slack conversation
"Can you disable that feature flag in production? We're seeing a performance regression."
More mistakes(2)
Handle with care. Do not confuse with a bug fix or hotfix. A feature flag is a toggle mechanism, not the actual fix itself. Also, it is not the same as a release branch.
- ✕The feature flag controls which database we use.✓The feature flag controls whether users see the new UI or the old one.
Feature flags toggle user-facing behavior, not infrastructure decisions. Infrastructure choices are separate.
- ✕We removed the feature flag after launch.✓We removed the feature flag code after confirming no users experienced issues.
Feature flags should be cleaned up from code once they are no longer needed, not just disabled.
Other forms(3)
- feature flag noun
"This feature flag controls access to the beta dashboard."
- to feature flag something verb phrase
"We will feature flag the API changes before deploying to production."
- feature-flagged adjective
"The new checkout flow is feature-flagged and visible only to admins."
Often used with(5)
- behind a feature flag · means the feature is hidden or controlled by a flag; most common phrasing in tech
- enable/disable a feature flag · to turn the flag on or off in a control system
- toggle a feature flag · to switch between on and off states
- feature flag rollout · the gradual process of activating a flag for increasing numbers of users
- feature flag management · the systems and processes for controlling flags across environments
Similar words(3)
- kill switch · informal term, emphasizes the ability to turn something off quickly in an emergency
- feature toggle · synonym often used interchangeably, slightly more formal
- conditional feature release · more descriptive term; less commonly used in conversation
Opposites(2)
- hard-coded feature
- unconditional deployment
Questions(5)
- What does feature flag mean in software engineering?
- A feature flag is a code switch that turns a feature on or off without redeploying. It lets teams safely deploy new code to production while keeping features hidden until they are ready for users. Feature flags reduce deployment risk and enable faster iteration.
- How do you use feature flag in a sentence at work?
- You can say: 'We shipped the feature behind a flag,' 'Let us feature flag that change,' or 'Toggle the flag to enable the new UI.' These are natural ways engineers discuss controlling feature visibility.
- Is feature flag formal or informal?
- Feature flag is neutral and professional. It is used in standup meetings, code reviews, and architecture discussions. While not academic or highly formal, it is the standard term in the industry, not slang.
- What is the difference between a feature flag and a kill switch?
- They are similar. A kill switch is more informal and emphasizes emergency shutdown, while feature flag is the broader technical term. Feature flags are used for gradual rollouts and testing; kill switches are for stopping something quickly if needed.
- Why are feature flags important in continuous deployment?
- Feature flags decouple deployment from release. Code can be deployed to production multiple times a day, but features remain hidden until the team is confident. This reduces the risk of large releases and enables real-world testing before exposing features to all users.
