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T3 Env — validate environment variables and encode server/client boundaries in types

OSS scale score 191.8OSS health 44Update pace 0 commits/30d
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Stars
4,005
Primary language
TypeScript
License
MIT
Repository last updated
Apr 1, 2026

Overview

T3 Env validates environment variables against schemas at runtime and exposes the validated result through TypeScript types, with explicit separation between server-only and client-visible variables.

Features and best fit

Based on official documentation; not hands-on tested · Content checked:

Validate environment variables against schemas during startup/build

Required values, URLs, defaults, transforms, and other constraints can fail configuration early rather than at runtime deep inside the application.

Sources: [2][3]

Encode server-only and client-visible variables separately

Client prefixes and runtime environment mappings make the boundary between browser-safe values and server secrets explicit.

Sources: [2][3]

For TypeScript applications that want configuration mistakes caught before production

It suits applications that want to replace raw process.env strings/undefined with validated, inferred configuration values.

Sources: [2]

Account for ESM/module resolution and secret exposure through client bundles

The package is ESM-only, and incorrect client-prefix/runtime configuration can expose secrets. Review framework bundling rules carefully.

Sources: [2][3]

Official sources

  1. [1]t3-oss/t3-env repository(2026-09-21)
  2. [2]T3 Env README(2026-09-21)
  3. [3]T3 Env documentation(2026-09-21)
  4. [4]Standard Schema(2026-09-21)
  5. [5]T3 Env MIT license(2026-09-21)
Supplemental curator note

T3 Env catches missing or invalid environment variables earlier in build/deploy workflows. It is ESM-only and requires module resolution that understands `package.json#exports`. Client-exposed variables must also be configured carefully so server secrets are not accidentally bundled.

Try it in 3 steps

  1. 1

    Get the source

    git clone --depth 1 https://github.com/t3-oss/t3-env.git
  2. 2

    Enter the repository

    cd t3-env
  3. 3

    Check the official steps

    Continue with the commands in the README Installation, Quick Start, or Getting Started section.

    find . -maxdepth 1 -iname 'README*' -exec sed -n '1,220p' {} \; -quit
Check the official README

Growth

Growth trends · Last 30 days

4,005 Stars

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Development activity

Last 90 days · weekly

Commits (last 30 days)
0
Open PRs
7

Development activity is still being collected.

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GitHub data

GitHub dataView detailed GitHub data
View on GitHub
Stars
4,005
Forks
128
Watchers
6
Open issues
24
Contributors
57
Primary language
TypeScript
License
MIT
Repository last updated
Apr 1, 2026
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