Evaluating TypeScript Feature Flag Tools

We've all been there: inheriting a codebase littered with if (process.env.ENABLE_NEW_FEATURE === 'true') statements scattered across dozens of files, or worse, finding feature flags that have been "temporarily" hardcoded for the past 18 months. The choice of feature flagging tool can make the difference between a clean, maintainable codebase and a technical debt nightmare. But there are a lot of options, so how do you evaluate them all?

A quick ChatGPT query will tell you to consider language and framework support, users and flag usage, data residency, hosted or self-hosted, regulatory compliance, budget and pricing, access controls, etc. And they’re all important considerations, but when it comes to finding the best TypeScript feature flagging tools, here are some things you should pay close attention to.

TypeScript integration quality

When evaluating any tool for a TypeScript codebase, the quality and type of integration isn't just nice-to-have, it's essential for maintaining code quality and developer productivity. What to look out for:

Auto-generated types vs. Manual type definition maintenance

For example, Reflag's approach here is CLI-first. When you run the command to create a flag:

npx reflag new "Advanced Search"

It automatically generates a flags.d.ts file with proper TypeScript definitions. This type safety means your IDE immediately understands your flag names, providing autocomplete and flag key typos become build errors. This guarantees that if you try to use a non-existent flag key, you'll receive a type error, preventing potential runtime errors and improving code reliability. For remote config, it also ensures that the shape of the payload defined on Reflag matches what your code expects.

Compare this to traditional approaches where you manually maintain type definitions, often leading to mismatches between your flag service and your code. Many feature flag services require you to manually define and maintain your flag types, while some open-source options rely on community-maintained type definitions.

Workflow support

Reflag supports a range of workflows. You can create flags in the UI, but also with the CLI, in Linear with an agent, or in your editor with MCP.

Let’s take a look at the CLI, for example:

# Initialize project
npx reflag init

Then, create flag and generate types in one command:

npx reflag new "Feature Name"

Or generate types after changes:

npx reflag types generate

It's recommended that you do not check in the flag types, but instead generate them in your build process and on your local development machines. So next we’ll add the generated files to .gitignore.

echo "gen/flags.d.ts" >> .gitignore

Traditional tools require you to context-switch to their web dashboard to create flags, then manually update your code to reference them. While this works, it breaks the development flow and creates opportunity for mismatches.

Use in CI/CD pipelines

The Reflag CLI is designed to work seamlessly in CI/CD pipelines and with coding agents. For automated environments where interactive login is not possible, you can use the --api-key option or specify the API key in the REFLAG_API_KEY environment variable e.g.

# Generate types in CI/CD
npx reflag apps list --api-key $REFLAG_API_KEY

In GitHub Actions, it looks like this:

- name: Generate types  
  run: npx reflag flags types --api-key ${{ secrets.REFLAG_API_KEY }}

Linear integration

If your team uses Linear, Reflag's tight integration means you can create feature flags by mentioning @reflag in Linear issues, e.g.:

@reflag create flag for advanced search feature

The agent creates the flag, suggests appropriate targeting rules, and updates the issue with implementation details.

IDE and Coding Agent integration

Reflag also supports MCP (Model Context Protocol) for IDE integration and use with coding agents. This means you can create and manage feature flags directly from your code editor without leaving your development environment. For teams using Cursor or other MCP-enabled IDEs, this is a significant productivity boost.

Flag lifecycle management

Something else to look out for, is how the service helps you to manage stale flags. Traditional feature flags create technical debt. Teams create flags for releases, ship the features, but rarely clean up the flag code. Over time, you end up with:

• Dead code paths that can't be reached
• Complex conditional logic that's hard to reason about  
• Security risks from unused code branches
• Performance overhead from unnecessary evaluations

Most vendors try to tackle this with little helpers. Usually they’re CLI tools that highlight mentions of feature keys in your code, while some also show you which flags haven’t been accessed in some time. But these don’t actually solve the problem, you still have to clean up the flags yourself.

Reflag, however, puts flag maintenance on autopilot with self-cleaning flags. Stale flags are auto-detected and it generates cleanup PRs for you. Implementation-wise, this requires Reflag to understand your codebase structure, which is why the TypeScript-first approach works so well. The generated types and CLI integration provide the context needed for intelligent code cleanup.

Implementation strategy

Once you’ve got your list of possible solutions down to a few, we suggest you try them out by flagging one, non-critical feature. That’s enough for you to get started and evaluate the developer experience.

Conclusion

The TypeScript ecosystem is maturing rapidly, and tools purpose-built for modern TypeScript development workflows offer significant productivity advantages. Reflag's approach of combining CLI-first workflows, automatic type generation, self-cleaning flags, and agent integration—represents where TypeScript tooling is heading.

A feature flagging tool that integrates cleanly with TypeScript, reduces technical debt, and supports AI-driven development workflows isn't just a nice-to-have—it's an investment in long-term codebase maintainability and team productivity.

When deciding on a TypeScript feature flag tool, keep in mind the TypeScript integration quality, workflow support, and flag lifecycle management that will best serve your team's specific TypeScript development practices and long-term technical goals.