# Environment Variables > For AI agents: see [llms.txt](/llms.txt) for the complete documentation index. Markdown versions are available by adding .md to a page URL or requesting Accept: text/markdown. Environment variables are key-value pairs that are useful for storing values you wouldn't want to put in code or in a table, such as an API key. You can set environment variables in Convex through the dashboard and access them in [functions](/functions/overview.md). For the best experience, [declare your environment variables](#declaring) in `convex/convex.config.ts` to get type-safe access via the generated `env` object. You can also access any environment variable via `process.env`. ## Setting environment variables[​](#setting-environment-variables "Direct link to Setting environment variables") Under [Deployment Settings](/dashboard/deployments/deployment-settings.md) in the Dashboard, you can see a list of environment variables in the current deployment. ![Environment variables table](/screenshots/storybook/components_deployment_environment_variables_light.webp) You can add up to 512 environment variables, and the total size of all environment variables (names + values) cannot exceed 512KiB. Environment variable names cannot be more than 256 characters long, and they must start with a letter and only contain letters, numbers, and underscores. Environment variable values cannot be larger than 8KiB. You can modify environment variables using the pencil icon button: ![Edit environment variable](/screenshots/storybook/components_deployment_environment_variables_edit_inline_light.webp) Environment variables can also be viewed and modified from the [command line](/cli/reference/env.md). ``` npx convex env list npx convex env get NAME npx convex env set NAME 'value' npx convex env set --from-file .env.convex npx convex env remove NAME ``` ### Using environment variables in dev and prod deployments[​](#using-environment-variables-in-dev-and-prod-deployments "Direct link to Using environment variables in dev and prod deployments") Since environment variables are set per-deployment, you can use different values for the same key in dev and prod deployments. This can be useful for when you have different external accounts you'd like to use depending on the environment. For example, you might have a dev and prod SendGrid account for sending emails, and your function expects an environment variable called `SENDGRID_API_KEY` that should work in both environments. If you expect an environment variable to be always present in a function, you must add it to **all** your deployments. In this example, you would add an environment variable with the name `SENDGRID_API_KEY` to your dev and prod deployments, with a different value for dev and prod. ## Declaring environment variables[​](#declaring "Direct link to Declaring environment variables") You can declare the environment variables your app expects in `convex/convex.config.ts`. Declared environment variables give you type-safe access, validation at deploy time, and clear documentation of what your app needs to run. This also helps prevent removing required environment variables or setting them to invalid values from the dashboard or `npx convex env [remove|set] ...`. convex/convex.config.ts ``` import { defineApp } from "convex/server"; import { v } from "convex/values"; const app = defineApp({ env: { GIPHY_KEY: v.string(), LOG_LEVEL: v.optional( v.union(v.literal("debug"), v.literal("info"), v.literal("error")), ), }, }); export default app; ``` The `env` option maps variable names to validators from `convex/values`. The supported validators are: * `v.string()` — any string value * `v.literal("value")` — an exact string value * `v.union(v.literal("a"), v.literal("b"))` — one of several exact values * `v.optional(...)` — wraps any of the above to mark a variable as optional After running `npx convex dev`, Convex generates a typed `env` object that you import from `_generated/server`: convex/myFunction.ts ``` import { query, env } from "./_generated/server"; export const gifUrl = query({ args: {}, handler: async () => { // env.GIPHY_KEY is typed as `string` // env.LOG_LEVEL is typed as `"debug" | "info" | "error" | undefined` return ( "https://api.giphy.com/v1/gifs/translate?api_key=" + env.GIPHY_KEY + "&s=cats" ); }, }); ``` The `env` import works in queries, mutations, actions, and HTTP actions. TypeScript will catch typos and type mismatches at build time rather than at runtime. You still need to [set the actual values](#setting-environment-variables) in the dashboard or CLI — declaring them in `convex.config.ts` defines what's expected, not what the values are. note Declaring environment variables is optional. If you don't declare them, you can still access all environment variables via `process.env` as described [below](#accessing-via-process-env), just without any guarantees about what value they contain. ### Passing environment variables to components[​](#component-env-vars "Direct link to Passing environment variables to components") [Components](/components/overview.md) are isolated from the app's environment variables. When a component declares environment variables in its `convex.config.ts`, you can provide environment variables when installing it: convex/convex.config.ts ``` import { defineApp } from "convex/server"; import { v } from "convex/values"; import myComponent from "@example/my-component/convex.config"; const app = defineApp({ env: { LOG_LEVEL: v.union( v.literal("debug"), v.literal("info"), v.literal("error"), ), }, }); // Pass by reference — the component's LOG_SEVERITY will always // match this app's LOG_LEVEL - even when it changes between deploys. app.use(myComponent, { env: { LOG_SEVERITY: app.env.LOG_LEVEL } }); export default app; ``` You can also populate component environment variables via literal values: convex/convex.config.ts ``` // Pass a literal value app.use(myComponent, { env: { LOG_SEVERITY: "debug" } }); ``` See [Authoring Components: Environment Variables](/components/authoring.md#environment-variables) for how to declare environment variables in a component. ## Accessing environment variables via `process.env`[​](#accessing-via-process-env "Direct link to accessing-via-process-env") You can access environment variables in Convex functions using `process.env.KEY`. If the variable is set it is a `string`, otherwise it is `undefined`. Here is an example of accessing an environment variable with the key `GIPHY_KEY`: ``` function giphyUrl(query) { return ( "https://api.giphy.com/v1/gifs/translate?api_key=" + process.env.GIPHY_KEY + "&s=" + encodeURIComponent(query) ); } ``` tip If you've [declared your environment variables](#declaring) in `convex.config.ts`, prefer using the typed `env` import from `_generated/server` instead of `process.env` for better type safety. You can use the [`@convex-dev/no-process-env`](/eslint.md#no-process-env) ESLint rule to automatically flag `process.env` reads, and suggest using `env.*` instead. Note that you should not condition your Convex function exports on environment variables. The set of Convex functions that can be called is determined during deployment and is not reevaluated when you change an environment variable. The following code will throw an error at runtime, if the DEBUG environment variable changes between deployment and calling the function. ``` // THIS WILL NOT WORK! export const myFunc = process.env.DEBUG ? mutation(...) : internalMutation(...); ``` Similarly, environment variables used in cron definitions will only be reevaluated on deployment. ## System environment variables[​](#system-environment-variables "Direct link to System environment variables") The following environment variables are always available in Convex functions: * `CONVEX_CLOUD_URL` - Your deployment URL (eg. `https://dusty-nightingale-847.convex.cloud`) for use with Convex clients. * `CONVEX_SITE_URL` - Your deployment site URL (eg. `https://dusty-nightingale-847.convex.site`) for use with [HTTP Actions](/functions/http-actions.md) ## Project environment variable defaults[​](#project-environment-variable-defaults "Direct link to Project environment variable defaults") You can set up default environment variable values for a project in Project Settings. ![Project default environment variables](/screenshots/storybook/components_project_default_environment_variables_light.webp) These default values will be used when creating a new deployment, and will have no effect on existing deployments (they are not kept in sync). You can set a different default value for each [deployment type](/production/multiple-deployments.md#deployment-types). The Deployment Settings will indicate when a deployment has environment variables that do not match the project defaults. ![Environment variable default mismatch](/screenshots/storybook/components_deployment_environment_variables_with_default_diff_light.webp) You can also change the default environment variables from the CLI using `npx convex env default`.