Stop hard-coding flag keys as loose strings. checkgate typegen reads your flag definitions — straight from a running server or a local JSON export — and emits a typed module so a wrong key or a mis-typed value is a compile error, not a production surprise.

Installation

npm install -g @checkgate/cli
# or run without installing:
npx @checkgate/cli typegen --help

Requires Node 18+ (uses the built-in fetch). Zero runtime dependencies.

Usage

checkgate typegen --lang <langs> [source] [output]

Pick a source

From a running server, authenticated with a personal access token (or SDK key):

checkgate typegen --lang ts \
  --url http://localhost:3000 \
  --env <environment-id> \
  --token <personal-access-token> \
  --out src/flags.ts

Or from a local JSON file (e.g. a /flags API export), which needs no network — ideal for CI:

checkgate typegen --lang ts,dart,rust --input flags.json --out-dir ./generated

Server connection details can also come from the environment: CHECKGATE_URL, CHECKGATE_ENV, CHECKGATE_TOKEN.

Options

| Flag | Alias | Description | |---|---|---| | --lang | -l | ts|typescript, dart, rust|rs. Comma-separate for several. | | --input | -i | Read flags from a local JSON file instead of the API. | | --url | -u | Server base URL (CHECKGATE_URL). | | --env | -e | Environment id to read (CHECKGATE_ENV). | | --token | -t | Personal access token / SDK key (CHECKGATE_TOKEN). | | --out | -o | Write to a file (single language); omit to print to stdout. | | --out-dir | | Write flags.<ext> per language (required for multiple languages). | | --help | -h | Show help. | | --version | | Show version. |

What it generates

Given a boolean new-dashboard, a string checkout-color, an integer max_items, and a JSON theme-config:

TypeScript

export type FlagKey = "new-dashboard" | "checkout-color" | "max_items" | "theme-config"

export interface FlagValueTypes {
  "new-dashboard": boolean
  "checkout-color": string
  "max_items": number
  "theme-config": unknown
}

export const FLAG_DEFAULTS = { /* each flag's configured default */ }

export function typedFlags(client: CheckgateLike) { /* … */ }

Wrap your existing client for compile-time-checked keys and correctly-typed values:

import { CheckgateClient } from '@checkgate/node'
import { typedFlags } from './flags'

const flags = typedFlags(new CheckgateClient({ /* … */ }))

const color = flags.getValue('checkout-color', userId) // typed as string
flags.getValue('chekout-color', userId)                // ❌ compile error — typo caught

Dart

A FlagKey enum, a kFlagDefaults map, and a TypedFlags wrapper with one strongly-typed getter per flag:

final flags = TypedFlags(checkgate);
final String color = flags.checkoutColor(userId);

Rust

A FlagKey enum (as_str(), ALL, Display) plus a defaults module of typed constants — dependency-free (json flags' defaults are emitted as raw JSON string constants):

let key = FlagKey::CheckoutColor.as_str(); // "checkout-color"
let fallback = defaults::CHECKOUT_COLOR;   // "blue"

Notes

• Output is deterministic — flags are sorted by key, so regenerating produces clean diffs. Regenerate in CI and check the result in, or fail the build on drift.
• Archived flags are excluded. Flags without a configured default_value fall back to a type-appropriate zero value (false / "" / 0 / null).
• Keys that aren't valid identifiers (hyphens, leading digits) are converted safely and de-duplicated per language.

Part of Checkgate — the self-hosted feature-flag platform.