HCL / Terraform Converter + Formatter

How to use it

1. Pick a mode: Convert turns HCL into its JSON representation; Format rewrites the file in canonical HCL style.
2. Paste HCL or Terraform configuration into the input pane, or open a .tf, .hcl or .tfvars file — up to 1 MiB.
3. Press the action button — the first run fetches the 1.9 MB engine once; every later run reuses it from this tab.
4. Read the result in the output pane. A parse error shows the engine's own diagnostic with its input.hcl line,column position.
5. Copy the result or download it as .json or .tf, and share the mode with a link — the link never carries your configuration.

Paste HCL and get its JSON representation, or run the canonical formatter over a Terraform file — both powered by the genuine HashiCorp HCL library (v2.24.0) and the hcl2json converter (v0.6.9), compiled to WebAssembly and executed in a worker in this tab. Convert output is byte-identical to the hcl2json CLI, diagnostics arrive word for word, and your configuration is never uploaded.

How it works

The engine is not a re-implementation. The genuine hashicorp/hcl v2.24.0 library and the tmccombs/hcl2json v0.6.9 converter are compiled with Go's js/wasm target into one 7.4 MB WebAssembly artifact (1.9 MB compressed), which runs inside a Web Worker in this tab. The engine itself arrives in exactly two same-origin requests — the Go runtime shim and the wasm binary, both this site's own static assets — and after that the parser works entirely on this device. Against the native hcl2json binary, the executed test corpus converts 8 of 8 fixtures byte-identically, so what this page prints is what the CLI prints.

Convert emits the HCL JSON representation, the alternate input syntax every HCL tool accepts. Block types and labels become nested object keys — a resource "aws_s3_bucket" "logs" block lands under resource → aws_s3_bucket → logs — and repeated blocks of one type collect into arrays. Argument expressions are not evaluated: interpolations such as "${var.name}", function calls and for-expressions are carried as strings, exactly as the JSON syntax expects them. The upstream Simplify option, which would fold constant expressions, stays off because it is the hcl2json CLI's own default.

Format runs hclwrite.Format, the library terraform fmt uses, from the same pinned hcl v2.24.0. It works on tokens, not meaning: indentation collapses to two-space steps, runs of = signs inside a body align, spacing around operators normalizes — and nothing is renamed, reordered, validated or dropped. Heredoc bodies pass through untouched, comments stay where they were, and formatting an already-canonical file returns it unchanged, which the test corpus proves by running the formatter twice over every fixture.

Examples

resource "aws_s3_bucket" "logs" {
  bucket        = "my-app-logs"
  force_destroy = true

  tags = {
    Environment = "production"
  }
}

{
    "resource": {
        "aws_s3_bucket": {
            "logs": [
                {
                    "bucket": "my-app-logs",
                    "force_destroy": true,
                    "tags": {
                        "Environment": "production"
                    }
                }
            ]
        }
    }
}

resource "aws_iam_policy" "readonly" {
name = "readonly"
policy = <<EOT
{
  "Version": "2012-10-17"
}
EOT
}

resource "aws_iam_policy" "readonly" {
  name   = "readonly"
  policy = <<EOT
{
  "Version": "2012-10-17"
}
EOT
}

variable "region" {
      type    = string
   default = "eu-central-1"
}

variable "region" {
  type    = string
  default = "eu-central-1"
}

Every example on this page is executed against the same engine that powers the tool, on every build.

Common errors

The input is empty — paste HCL or Terraform configuration first.

Both modes need text first. Load the sample to see the shape the parser expects, or drop a .tf file straight onto the input pane.

parse config: [input.hcl:1,33-34: Unclosed configuration block; There is no closing brace for this block before the end of the file. This may be caused by incorrect brace nesting elsewhere in this file.]

The engine's own text, word for word — input.hcl is this page's name for the pasted text, and 1,33 reads line 1, column 33. A missing closing brace is usually the LAST brace of the file, but the parser points at the block it could not close.

parse config: [input.hcl:2,3-7: Argument or block definition required; An argument or block definition is required here. To set an argument, use the equals sign "=" to introduce the argument value.]

HCL native syntax separates arguments with =, not the colon JSON uses — name: "x" inside a block is the classic YAML/JSON habit this diagnostic catches. Write name = "x" instead.

parse config: [input.hcl:2,9-3,1: Invalid expression; Expected the start of an expression, but found an invalid expression token.]

An = with nothing after it: the parser reached the line break still waiting for a value. The 2,9-3,1 span shows exactly where the expression should have started and where the parser gave up.

Input is larger than the 1 MiB limit for this tool. For bigger files use the CLI: hcl2json main.tf

The cap keeps a worst-case parse inside the 10-second kill window. Terraform configurations are normally far smaller; a bigger corpus belongs to the CLI on your machine, which has no such limit.

The run took longer than 10 seconds and was stopped — split the configuration and try again.

A WebAssembly call cannot be paused, so a runaway parse is ended by terminating the worker after 10 seconds. The next run reloads the engine from the browser cache and your input stays put.

Keyboard shortcuts

⌘/Ctrl + Enter

Convert or format now, per the selected mode.

⌘/Ctrl + S

Download the result as .json or .tf.

⌘/Ctrl + C

Copy the result when nothing is selected.

⌘/Ctrl + Shift + C

Copy the result even with a selection active.

/

Focus the HCL input.

t

Cycle the color theme.

? or ⌘/Ctrl + /

Show the shortcut overlay.

Esc

Cancel a run, or dismiss a banner.