> ## 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.

# FunC language overview

export const Image = ({src, darkSrc, alt = '', darkAlt, href, target, height = 342, width = 608, noZoom = false, center = false}) => {
  const isSVG = src.match(/\.svg(?:[#?].*?)?$/i) !== null;
  const shouldInvert = isSVG && !darkSrc;
  const shouldCreateLink = href !== undefined;
  const minPx = 9;
  const maxPx = 608;
  const expectedPx = `a number or a string with a number that is greater than ${minPx - 1} and less than or equal to ${maxPx}`;
  const createInvalidPropCallout = (title, received, expected) => {
    return <Danger>
        <span className="font-bold">
          Invalid <code>{title.toString()}</code> passed!
        </span>
        <br />
        <span className="font-bold">Received: </span>
        {received.toString()}
        <br />
        <span className="font-bold">Expected: </span>
        {expected.toString()}
        {}
      </Danger>;
  };
  const checkValidDimensionValue = value => {
    switch (typeof value) {
      case "string":
      case "number":
        const num = Number(value);
        return Number.isSafeInteger(num) && num >= minPx && num <= maxPx;
      default:
        return false;
    }
  };
  let callouts = [];
  if (height && !checkValidDimensionValue(height)) {
    callouts.push(createInvalidPropCallout("height", height, expectedPx));
  }
  if (width && !checkValidDimensionValue(width)) {
    callouts.push(createInvalidPropCallout("width", width, expectedPx));
  }
  if (callouts.length !== 0) {
    return callouts;
  }
  const heightPx = Number(height);
  const widthPx = Number(width);
  const shouldCenter = center === "true" || center === true ? true : false;
  const shouldNotZoom = noZoom === "true" || noZoom === true ? true : false;
  const images = <>
      <img className="block dark:hidden" src={src} alt={alt} {...height && ({
    height: heightPx
  })} {...width && ({
    width: widthPx
  })} {...(shouldCreateLink || shouldInvert || shouldNotZoom) && ({
    noZoom: "true"
  })} />
      <img className={`hidden dark:block ${shouldInvert ? "invert" : ""}`} src={darkSrc ?? src} alt={darkAlt ?? alt} {...height && ({
    height: heightPx
  })} {...width && ({
    width: widthPx
  })} {...(shouldCreateLink || shouldInvert || shouldNotZoom) && ({
    noZoom: "true"
  })} />
    </>;
  if (shouldCreateLink) {
    if (shouldCenter) {
      return <div style={{
        display: "flex",
        justifyContent: "center"
      }}>
          <a href={href} target={target ?? "_self"}>
            {images}
          </a>
        </div>;
    }
    return <a href={href} target={target ?? "_self"}>
        {images}
      </a>;
  }
  if (shouldCenter) {
    return <div style={{
      display: "flex",
      justifyContent: "center"
    }}>{images}</div>;
  }
  return images;
};

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="note">
  The official smart contract language of TON Blockchain is [Tolk](/tolk/overview). FunC is now a **legacy** language, with its compiler no longer maintained.

  FunC pages will be moved down in the sidebar in mid-April 2026. Here is the preview of a possible future placement, right between "Blockchain foundations" and "Contribute" sections:

  <Image src="/resources/images/tmp-func-fift-light.png" darkSrc="/resources/images/tmp-func-fift-dark.png" alt="Preview of a possible future placement of FunC and Fift languages in the sidebar." width={294} height={190} noZoom={true} />

  Learn how to [migrate from FunC to Tolk](/tolk/from-func/tolk-vs-func).
</Aside>

FunC is a domain-specific, statically typed language with C-like syntax designed to write smart contracts on TON. It can be characterized as an intermediate-level language sitting on top of the [Fift](/languages/fift) assembly language.

Example of a FunC function for sending funds:

```func 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"]}}
() send_money(slice address, int amount) impure inline {
    var msg = begin_cell()
        ;; Set the message to be non-bounceable
        .store_uint(0x10, 6)
        .store_slice(address)
        .store_coins(amount)
        .end_cell();

    send_raw_message(msg, 64);
}
```

where

* [`()`](/languages/func/types#tensor-types) is the return type, that stands for "do not return value", similar to `void` in C;
* `send_money` is the name of the function;
* `slice address` is the first parameter, address to send money to; it's type is [`slice`](/languages/func/types#atomic-types);
* `int amount` is the second parameter, amount to be sent; it's type is [`int`](/languages/func/types#atomic-types);
* `impure inline` are [specifiers](/languages/func/functions#specifiers), which are flags that tell the compiler to process the method in a specific way;
* `var msg = ...` defines a variable without specifying its type; it will hold a [cell](/foundations/serialization/cells) with a [message](/foundations/messages/overview);
* [`begin_cell()`](/languages/func/stdlib#begin-cell) creates a [cell builder](/tvm/builders-and-slices);
* [`store_uint`](/languages/func/stdlib#store-uint), [`store_slice`](/languages/func/stdlib#store-slice), [`store_coins`](/languages/func/stdlib#store-coins) methods store data into the builder:
  * [flags](/foundations/messages/internal);
  * receiving address;
  * amount on Toncoin to attach to the message.
* [`.end_cell()`](/languages/func/stdlib#end-cell) method finalizes the builder and turns it into a cell;
* [`send_raw_message`](/languages/func/stdlib#send-raw-message) function sends the message, where the parameter `64` describes a [sending mode](/foundations/messages/internal).

## Compiler

The compiler converts FunC programs into [Fift](/languages/fift) assembly code. The Fift assembly code is then compiled down to the [TON Virtual Machine](/tvm/overview) bitcode by the [Fift](/languages/fift) compiler.

Developers can use the compiled bitcode, structured as a [bag of cells](/foundations/serialization/boc) like all data in the TON blockchain, to test smart contracts, send messages, or execute it in a local TVM instance.

### End-to-end tooling

The easiest way to install the FunC compiler is the [`@ton-community/func-js`](https://www.npmjs.com/package/@ton-community/func-js) NPM package. It requires [Node.js](https://nodejs.org/en/download) v22 or later.

The package has both the FunC and [Fift](/languages/fift) compilers, and produces bitcode directly from the FunC source code, without manually invoking Fift.

To install it, run the following command in the project root folder:

```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 @ton-community/func-js
```

Then, to compile a specific FunC file, run the following command:

```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"]}}
npx func-js ./contract.fc --boc ./output.boc
```

where `contract.fc` is the FunC source file in the project root, and `output.boc` is the compiled bitcode output.

FunC standard library is supplied separately from the language. Download `smartcont_lib.zip` from the [latest release](https://github.com/ton-blockchain/ton/releases), extract it, and copy `stdlib.fc` to the project root.

Alternatively, use the [Blueprint](/contract-dev/blueprint/overview) to start a project pre-configured for development in FunC.

### Compile manually using the binaries

Prebuilt FunC compiler binaries for Windows, macOS (Intel or ARM64), and Ubuntu are available on the [GitHub](https://github.com/ton-blockchain/ton/releases).

1. Download the corresponding binary for operating system:

   * Linux: `func-linux-x86_64` (Intel/AMD) and `func-linux-arm64` (ARM64)
   * Mac: `func-mac-x86-64` (Intel/AMD) and `func-mac-arm64` (ARM64)
   * Windows: `func.exe`

   Rename the executable, for example, to `func`, for easier use on the command line, and add it to system's `PATH`.

2. Download the FunC standard library.

   Get the `smartcont_lib.zip` from the same [GitHub](https://github.com/ton-blockchain/ton/releases/tag/v2025.07), extract it, and copy `stdlib.fc` to project root.

3. Compile a FunC file to Fift assembly code.

   Run the following command in the project root:

```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"]}}
func contract.fc -o output.fif
```

where `contract.fc` is the FunC file to compile, and `output.fif` is the generated Fift output.

To compile the generated Fift file `output.fif` further down to TVM bitcode, use the Fift compiler. See the [Fift](/languages/fift) for download and usage instructions.

<Aside>
  The last FunC compiler version is v2025.07. The FunC compiler is no longer developed. New releases are focused on the [Tolk](https://github.com/ton-blockchain/ton/releases/latest) compiler.
</Aside>

## Tutorials

<Aside>
  The tutorials in this section are provided by external contributors and may not reflect FunC's current development status. They are offered as additional resources for exploring FunC's applications.
</Aside>

* [Challenge 1: Simple NFT deploy](https://github.com/romanovichim/TONQuest1/)
* [Challenge 2: Chatbot contract](https://github.com/romanovichim/TONQuest2/)
* [Challenge 3: Jetton vending machine](https://github.com/romanovichim/TONQuest3/)
* [Challenge 4: Lottery/raffle](https://github.com/romanovichim/TONQuest4/)
* [Challenge 5: Create UI to interact with the contract in 5 minutes](https://github.com/romanovichim/TONQuest5/)
* [Challenge 6: Analyzing NFT sales on the Getgems marketplace](https://github.com/romanovichim/TONQuest6/)
* [TON hello world Part 2: guide for writing your first smart contract](https://ton-community.github.io/tutorials/02-contract/)
* [TON hello world Part 4: guide for testing your first smart contract](https://ton-community.github.io/tutorials/04-testing/)
* [10 lessons for developing contracts in FunC](https://github.com/romanovichim/TonFunClessons_Eng/) — [Russian version](https://github.com/romanovichim/TonFunClessons_ru/)
* [FunC quiz](https://t.me/toncontests/60/) — a short Telegram quiz focused on FunC, with a few general TON questions.

## Contests

| Contest           | Tasks                                                     | Solutions                                                                                                                                                           |
| :---------------- | :-------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| TSC #5 (Dec 2023) | [Tasks](https://github.com/ton-community/tsc5/)           | —                                                                                                                                                                   |
| TSC #4 (Sep 2023) | [Tasks](https://github.com/ton-community/tsc4/)           | [1](https://github.com/aSpite/tsc4-contracts) [2](https://github.com/ProgramCrafter/tsc4) [3](https://github.com/Gusarich/tsc4) [4](https://github.com/akifoq/tsc4) |
| TSC #3 (Dec 2022) | [Tasks](https://github.com/ton-blockchain/func-contest3/) | [Solutions](https://github.com/nns2009/TON-FunC-contest-3/)                                                                                                         |
| TSC #2 (Jul 2022) | [Tasks](https://github.com/ton-blockchain/func-contest2/) | [Solutions](https://github.com/ton-blockchain/func-contest2-solutions/)                                                                                             |
| TSC #1 (Mar 2022) | [Tasks](https://github.com/ton-blockchain/func-contest1/) | [Solutions](https://github.com/ton-blockchain/func-contest1-solutions/)                                                                                             |

## Changelog

[History of FunC](/languages/func/changelog)