> ## Documentation Index
> Fetch the complete documentation index at: https://companyname-a7d5b98e-security-edits.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Tact language

export const Aside = ({type = "note", title = "", icon = "", iconType = "regular", children}) => {
  const asideVariants = ["note", "tip", "caution", "danger"];
  const asideComponents = {
    note: {
      outerStyle: "border-sky-500/20 bg-sky-50/50 dark:border-sky-500/30 dark:bg-sky-500/10",
      innerStyle: "text-sky-900 dark:text-sky-200",
      calloutType: "note",
      icon: <svg width="14" height="14" viewBox="0 0 14 14" fill="currentColor" xmlns="http://www.w3.org/2000/svg" className="w-4 h-4 text-sky-500" aria-label="Note">
          <path fill-rule="evenodd" clip-rule="evenodd" d="M7 1.3C10.14 1.3 12.7 3.86 12.7 7C12.7 10.14 10.14 12.7 7 12.7C5.48908 12.6974 4.0408 12.096 2.97241 11.0276C1.90403 9.9592 1.30264 8.51092 1.3 7C1.3 3.86 3.86 1.3 7 1.3ZM7 0C3.14 0 0 3.14 0 7C0 10.86 3.14 14 7 14C10.86 14 14 10.86 14 7C14 3.14 10.86 0 7 0ZM8 3H6V8H8V3ZM8 9H6V11H8V9Z"></path>
        </svg>
    },
    tip: {
      outerStyle: "border-emerald-500/20 bg-emerald-50/50 dark:border-emerald-500/30 dark:bg-emerald-500/10",
      innerStyle: "text-emerald-900 dark:text-emerald-200",
      calloutType: "tip",
      icon: <svg width="11" height="14" viewBox="0 0 11 14" fill="currentColor" xmlns="http://www.w3.org/2000/svg" className="text-emerald-600 dark:text-emerald-400/80 w-3.5 h-auto" aria-label="Tip">
          <path d="M3.12794 12.4232C3.12794 12.5954 3.1776 12.7634 3.27244 12.907L3.74114 13.6095C3.88471 13.8248 4.21067 14 4.46964 14H6.15606C6.41415 14 6.74017 13.825 6.88373 13.6095L7.3508 12.9073C7.43114 12.7859 7.49705 12.569 7.49705 12.4232L7.50055 11.3513H3.12521L3.12794 12.4232ZM5.31288 0C2.52414 0.00875889 0.5 2.26889 0.5 4.78826C0.5 6.00188 0.949566 7.10829 1.69119 7.95492C2.14321 8.47011 2.84901 9.54727 3.11919 10.4557C3.12005 10.4625 3.12175 10.4698 3.12261 10.4771H7.50342C7.50427 10.4698 7.50598 10.463 7.50684 10.4557C7.77688 9.54727 8.48281 8.47011 8.93484 7.95492C9.67728 7.13181 10.1258 6.02703 10.1258 4.78826C10.1258 2.15486 7.9709 0.000106649 5.31288 0ZM7.94902 7.11267C7.52078 7.60079 6.99082 8.37878 6.6077 9.18794H4.02051C3.63739 8.37878 3.10743 7.60079 2.67947 7.11294C2.11997 6.47551 1.8126 5.63599 1.8126 4.78826C1.8126 3.09829 3.12794 1.31944 5.28827 1.3126C7.2435 1.3126 8.81315 2.88226 8.81315 4.78826C8.81315 5.63599 8.50688 6.47551 7.94902 7.11267ZM4.87534 2.18767C3.66939 2.18767 2.68767 3.16939 2.68767 4.37534C2.68767 4.61719 2.88336 4.81288 3.12521 4.81288C3.36705 4.81288 3.56274 4.61599 3.56274 4.37534C3.56274 3.6515 4.1515 3.06274 4.87534 3.06274C5.11719 3.06274 5.31288 2.86727 5.31288 2.62548C5.31288 2.38369 5.11599 2.18767 4.87534 2.18767Z"></path>
        </svg>
    },
    caution: {
      outerStyle: "border-amber-500/20 bg-amber-50/50 dark:border-amber-500/30 dark:bg-amber-500/10",
      innerStyle: "text-amber-900 dark:text-amber-200",
      calloutType: "warning",
      icon: <svg className="flex-none w-5 h-5 text-amber-400 dark:text-amber-300/80" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2" aria-label="Warning">
          <path stroke-linecap="round" stroke-linejoin="round" d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-3L13.732 4c-.77-1.333-2.694-1.333-3.464 0L3.34 16c-.77 1.333.192 3 1.732 3z"></path>
        </svg>
    },
    danger: {
      outerStyle: "border-red-500/20 bg-red-50/50 dark:border-red-500/30 dark:bg-red-500/10",
      innerStyle: "text-red-900 dark:text-red-200",
      calloutType: "danger",
      icon: <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" fill="currentColor" className="text-red-600 dark:text-red-400/80 w-4 h-4" aria-label="Danger">
          <path d="M17.1 292c-12.9-22.3-12.9-49.7 0-72L105.4 67.1c12.9-22.3 36.6-36 62.4-36l176.6 0c25.7 0 49.5 13.7 62.4 36L494.9 220c12.9 22.3 12.9 49.7 0 72L406.6 444.9c-12.9 22.3-36.6 36-62.4 36l-176.6 0c-25.7 0-49.5-13.7-62.4-36L17.1 292zm41.6-48c-4.3 7.4-4.3 16.6 0 24l88.3 152.9c4.3 7.4 12.2 12 20.8 12l176.6 0c8.6 0 16.5-4.6 20.8-12L453.4 268c4.3-7.4 4.3-16.6 0-24L365.1 91.1c-4.3-7.4-12.2-12-20.8-12l-176.6 0c-8.6 0-16.5 4.6-20.8 12L58.6 244zM256 128c13.3 0 24 10.7 24 24l0 112c0 13.3-10.7 24-24 24s-24-10.7-24-24l0-112c0-13.3 10.7-24 24-24zM224 352a32 32 0 1 1 64 0 32 32 0 1 1 -64 0z"></path>
        </svg>
    }
  };
  let variant = type;
  let gotInvalidVariant = false;
  if (!asideVariants.includes(type)) {
    gotInvalidVariant = true;
    variant = "danger";
  }
  const iconVariants = ["regular", "solid", "light", "thin", "sharp-solid", "duotone", "brands"];
  if (!iconVariants.includes(iconType)) {
    iconType = "regular";
  }
  return <>
      <div className={`callout my-4 px-5 py-4 overflow-hidden rounded-2xl flex gap-3 border ${asideComponents[variant].outerStyle}`} data-callout-type={asideComponents[variant].calloutType}>
        <div className="mt-0.5 w-4" data-component-part="callout-icon">
          {}
          {icon === "" ? asideComponents[variant].icon : <Icon icon={icon} iconType={iconType} size={14} />}
        </div>
        <div className={`text-sm prose min-w-0 w-full ${asideComponents[variant].innerStyle}`} data-component-part="callout-content">
          {gotInvalidVariant ? <p>
              <span className="font-bold">
                Invalid <code>type</code> passed!
              </span>
              <br />
              <span className="font-bold">Received: </span>
              {type}
              <br />
              <span className="font-bold">Expected one of: </span>
              {asideVariants.join(", ")}
            </p> : <>
              {title && <p className="font-bold">{title}</p>}
              {children}
            </>}
        </div>
      </div>
    </>;
};

<Aside type="danger" title="Deprecation notice">
  The official smart contract language of TON Blockchain is [Tolk](/tolk/overview), and the Tact language is being **deprecated**. This page will be removed in mid-April 2026.

  The dedicated [Tact documentation](https://docs.tact-lang.org) site remains available and will continue to be available in the future.

  Thank you for all the support. Those who built Tact stand proud, with deep gratitude to the TON community <Icon icon="heart" size={12} />
</Aside>

Tact is a programming language for TON Blockchain, focused on efficiency and ease of development. It is a good fit for complex smart contracts, quick onboarding and rapid prototyping.

Developed by [TON Studio](https://tonstudio.io), powered by the community — at the start of 2025, the number of *unique code*[^1] contracts deployed on the mainnet reached almost 28 thousand, of which about 33% were written in Tact. You can view some selected projects here: [Tact in production](#tact-in-production).

[^1]: The "unique code" means that each contract in the data sample has at least one TVM instruction that differs from the other contracts, excluding many preprocessed wallets with everything inlined — even seqno and a public key for signature verification!

Tact has undergone a comprehensive security audit by [Trail of Bits](https://www.trailofbits.com), a leading Web3 security firm.

<Columns cols={3}>
  <Card title="Try it online!" arrow="true" href="https://ide.ton.org/" />

  <Card title="Tact documentation" arrow="true" href="https://docs.tact-lang.org/" />

  <Card title="Awesome Tact" arrow="true" href="https://github.com/tact-lang/awesome-tact" />
</Columns>

## Features

The most prominent and distinctive features of Tact are:

* Familiar and user-friendly TypeScript-like syntax.
* Strong static type system with built-in [Structs], [Messages], and [maps], among others.
* First-class [maps] support, with many methods and a convenient [`foreach` statement][foreach] for traversing.
* Automatic (de)serialization of incoming messages and data structures.
* Automatic routing of [internal, external, and bounced messages][recvfun].
* Automatic handling of message types, including [binary, text, and fallback slices][recv].
* No boilerplate functions for [sending messages] and deploying child contracts.
* Reusable behaviors through [traits].
* Support for low-level programming with [`asm` functions][asmfun].
* Generation of [single-file TypeScript wrappers] for convenient interactions with compiled contracts, which include:
  * Type definitions for [Structs] and [Messages] are observable in the [compilation report].
  * Corresponding `storeStructureName()` and `loadStructureName()` functions for (de)serialization.
  * All global and contract-level constants.
  * Bi-directional records of exit codes: from their names to numbers and vice versa.
  * Opcodes of all [Messages].
  * A contract wrapper class with various helper functions for initialization, deployment, and message exchange.
* Rich [standard library][stdlib].
* Extensive [documentation].
* Robust [tooling](#tooling).
* ...and there's much more to come!

[Structs]: https://docs.tact-lang.org/book/structs-and-messages#structs

[Messages]: https://docs.tact-lang.org/book/structs-and-messages#messages

[maps]: https://docs.tact-lang.org/book/maps

[foreach]: https://docs.tact-lang.org/book/statements#foreach-loop

[recv]: https://docs.tact-lang.org/book/receive/

[recvfun]: https://docs.tact-lang.org/book/contracts/#receiver-functions

[sending messages]: https://docs.tact-lang.org/book/send/#message-sending-functions

[traits]: https://docs.tact-lang.org/book/types/#traits

[asmfun]: https://docs.tact-lang.org/book/assembly-functions/

[single-file TypeScript wrappers]: https://docs.tact-lang.org/book/compile/#wrap

[compilation report]: https://docs.tact-lang.org/book/compile/#report

[stdlib]: https://docs.tact-lang.org/ref/

[documentation]: https://docs.tact-lang.org/

## Security

* [Security audit of Tact by the Trail of Bits (2025, PDF)](https://github.com/trailofbits/publications/blob/master/reviews/2025-01-ton-studio-tact-compiler-securityreview.pdf)
  * Backup link: [PDF Report](https://github.com/tact-lang/website/blob/416073ed4056034639de257cb1e2815227f497cb/pdfs/2025-01-ton-studio-tact-compiler-securityreview.pdf)

## Tact in production

Some selected software and applications based on contracts written in Tact, deployed in production, and consumed by end users:

###### Open source or source available

* [Proof-of-capital](https://github.com/proof-of-capital/TON) - [proof-of-capital](https://proofofcapital.org/) is a market-making smart contract that protects the interests of all holders.
  * See the [security audit report](https://raw.githubusercontent.com/nowarp/public-reports/master/2025-01-proof-of-capital.pdf) by [Nowarp](https://nowarp.io).

###### Closed source

* [Tradoor](https://tradoor.io) - Fast and social DEX on TON.
  * See the [security audit report](https://www.tonbit.xyz/reports/Tradoor-Smart-Contract-Audit-Report-Summary.pdf) by TonBit.
* [PixelSwap](https://www.pixelswap.io) - First modular and upgradeable DEX on TON.
  * See the [security audit report](https://github.com/trailofbits/publications/blob/master/reviews/2024-12-pixelswap-dex-securityreview.pdf) by Trail of Bits.
* [GasPump](https://gaspump.tg) - TON memecoin launchpad and trading platform.

See [Tact in production](https://github.com/tact-lang/awesome-tact#tact-in-production-) on the Awesome Tact list.

## Installation

### Compiler

The Tact compiler is distributed as an [NPM package](https://www.npmjs.com/package/@tact-lang/compiler) bundled with the [Tact standard library](https://docs.tact-lang.org/ref/).

The recommended Node.js version is 22 or higher, while the minimum version is 18.

Use your favorite package manager to install it into a Node.js project:

```bash theme={"theme":{"light":"github-light-default","dark":"dark-plus"},"languages":{"custom":["/resources/grammars/tolk.tmLanguage.json","/resources/grammars/tlb.tmLanguage.json","/resources/grammars/fift.tmLanguage.json","/resources/grammars/tasm.tmLanguage.json","/resources/grammars/func.tmLanguage.json"]}}
# yarn is recommended, but not required
yarn add @tact-lang/compiler

# you can also use npm
npm i @tact-lang/compiler@latest

# or pnpm
pnpm add @tact-lang/compiler

# or bun
bun add @tact-lang/compiler
```

Alternatively, you can install it globally as such:

```bash theme={"theme":{"light":"github-light-default","dark":"dark-plus"},"languages":{"custom":["/resources/grammars/tolk.tmLanguage.json","/resources/grammars/tlb.tmLanguage.json","/resources/grammars/fift.tmLanguage.json","/resources/grammars/tasm.tmLanguage.json","/resources/grammars/func.tmLanguage.json"]}}
npm i -g @tact-lang/compiler
```

It will make the `tact` compiler available on your PATH, as well as:

* a convenient `unboc` disassembler of a contract's code compiled into a [bag of cells](/foundations/serialization/boc) `.boc` format.
* a formatter `tact-fmt`, which can format or check the formatting of individual Tact files and directories.

### Tooling

###### Extensions and plugins

* [VS Code extension](https://marketplace.visualstudio.com/items?itemName=tonstudio.vscode-tact) - powerful and feature-rich extension for Visual Studio Code (VSCode) and VSCode-based editors like VSCodium, Cursor, Windsurf, and others.
  * Get it on the [Visual Studio Marketplace](https://marketplace.visualstudio.com/items?itemName=tonstudio.vscode-tact).
  * Get it on the [Open VSX Registry](https://open-vsx.org/extension/tonstudio/vscode-tact).
  * Or install from the [`.vsix` files in nightly releases](https://github.com/tact-lang/tact-language-server/releases).
* [JetBrains IDEs plugin](https://plugins.jetbrains.com/plugin/27290-tact#) - provides syntax highlighting, code navigation, and more.
* [Language Server (LSP Server)](https://github.com/tact-lang/tact-language-server) - supports Sublime Text, (Neo)Vim, Helix, and other editors with LSP support.
* [tact.vim](https://github.com/tact-lang/tact.vim) - Vim 8+ plugin.
* [tact-sublime](https://github.com/tact-lang/tact-sublime) - Sublime Text 4 package.
  * Get it on the [Package Control](https://packagecontrol.io/packages/Tact).

###### Security

* [Misti](https://github.com/nowarp/misti) - Static smart contract analyzer.
* [TON Symbolic Analyzer (TSA)](https://github.com/espritoxyz/tsa) - Static smart contract analysis tool based on symbolic execution.

###### Utility

* Formatter (`tact-fmt`) — The official formatter. It ships with the Tact Language Server, VS Code extension, and as a standalone binary with the compiler. You can invoke it by running `npx tact-fmt` in your Tact projects.
* BoC Disassembler (`unboc`) — Disassembler for [`.boc`](/foundations/serialization/boc) files. Ships as a standalone binary with the compiler. You can invoke it by running `npx unboc` in your Tact projects.

### Getting started

For a quick start, read the ["Let's start!"](https://docs.tact-lang.org/#start) mini-guide in the Tact documentation. It uses the [Blueprint](https://github.com/ton-community/blueprint) development environment for writing, testing, and deploying smart contracts on TON Blockchain.

If you want more manual control, use [tact-template](https://github.com/tact-lang/tact-template). It's a ready-to-use template with the development environment set up, including the Tact compiler with TypeScript + Jest, a local TON emulator, AI-based editor support, and examples of how to run tests.

```shell theme={"theme":{"light":"github-light-default","dark":"dark-plus"},"languages":{"custom":["/resources/grammars/tolk.tmLanguage.json","/resources/grammars/tlb.tmLanguage.json","/resources/grammars/fift.tmLanguage.json","/resources/grammars/tasm.tmLanguage.json","/resources/grammars/func.tmLanguage.json"]}}
git clone --depth 1 https://github.com/tact-lang/tact-template
```

## Community

If you can’t find the answer in the [docs](https://docs.tact-lang.org), or you’ve tried to do some local testing and it still didn’t help, don’t hesitate to reach out to Tact’s flourishing community:

* [`@tactlang` on Telegram](https://t.me/tactlang) - Main community chat and discussion group.
* [`@tactlang_ru` on Telegram](https://t.me/tactlang_ru) *(Russian)*
* [`@tact_kitchen` on Telegram](https://t.me/tact_kitchen) - Channel with updates from the team.
* [`@tact_language` on X/Twitter](https://x.com/tact_language)
* [`tact-lang` organization on GitHub](https://github.com/tact-lang)
* [`@ton_studio` on Telegram](https://t.me/ton_studio)
* [`@thetonstudio` on X/Twitter](https://x.com/thetonstudio)

## Contributing

Contributions are welcome! To help develop the compiler, see the [contributing guide](https://github.com/tact-lang/tact/blob/main/dev-docs/CONTRIBUTING.md).