compiler-explorer.com

Compiler Explorer is a browser-based interactive compiler that shows the assembly output of your code as you type. You paste or write source code in one pane, pick a compiler and language, and the site compiles it server-side and displays the generated assembly (or other intermediate output) in a second pane. It supports C++, Rust, Go, and many other languages, and it requires no local installation — but it does need JavaScript, since the regular site is not functional without it.

What you can do with it

The core workflow is a two-pane editor: source on the left, compiler output on the right. From there, the tool exposes a wide range of views and options.

Core actions

• Write or paste code in the source editor and see compiled output update live.
• Choose from multiple compilers and language versions via the compiler selector.
• Switch the output view to assembly, binary object, or execute the code directly.
• Compare two versions of code side by side using the Diff View.
• Use Tree (IDE Mode) for a structured view of the compilation.

Output and analysis views

Beyond raw assembly, Compiler Explorer can show several intermediate representations and diagnostics, depending on the language and compiler:

The available views depend on the selected language and compiler — the site notes when the current language or compiler does not support a given tool.

Practical features

• Compiler flags: edit verbose compiler flags in a separate window, and use "Popular arguments" for common options.
• Libraries: add and manage libraries, with overrides.
• Execution: run compiled code and supply stdin and runtime arguments.
• Formatting: apply clang-format to your source.
• Sharing: generate a short link, full link, or an embeddable iframe.
• Save/Load and History: keep and revisit your work.
• Templates: start from a template rather than a blank editor.
• UI layout: reset the UI layout or reset both code and UI layout.

Output filtering and display options

The output pane has filters that matter when assembly gets noisy:

• Demangle identifiers (and verbose demangling).
• Intel asm syntax toggle.
• Filter unused labels, library functions, directives, comments, and horizontal whitespace.
• Show or hide debug intrinsics.
• Wrap lines.
• Download the output.

For optimization remarks, you can choose to show missed, passed, or analysis remarks. For LLVM IR, options include dumping the full module, demangling symbols, and -fno-discard-value-names.

Who it is for

• Learners who want to see what their C++, Rust, or Go code compiles to without setting up a toolchain.
• Developers comparing how different compilers or optimization levels handle the same code.
• Anyone debugging code generation, inlining, or optimization behavior.

Things to know before you start

• JavaScript is required for the regular site. A noscript version exists if you cannot use JavaScript.
• The site is funded through sponsorships and donations (Patreon, GitHub Sponsors, PayPal, and a shop); the page evidence does not state pricing or login requirements, so treat availability of any account-based features as unconfirmed.
• Some tools are language- or compiler-specific and will be unavailable for certain selections.

If you want to see assembly for a snippet right now, open the site, pick your language and compiler, paste the code, and read the output pane — that is the entire loop.

A postal code API returns structured location data for a given ZIP Code or Canadian postal code. A typical response includes the code itself, city, state or province, county, latitude/longitude, and — where available — ZIP+4 detail. More complete services add time zone, area codes, boundary geometry, and demographic fields. You send a code (or an address), and the API sends back a machine-readable record you can store, validate, or display.

This article explains what those responses contain, how requests are usually shaped, and where postal code data fits into real applications.

First, clear up the word "code"

The keyword "code" is overloaded, and that causes real confusion for developers:

• Postal code — the ZIP Code (U.S.) or postal code (Canada) that identifies a delivery area.
• API key — the credential you use to authenticate your requests. It is not postal data.
• Source code — the program you write to call the API.

When someone searches for "postal code API code," they usually want example request/response code for a postal code service. The rest of this article treats it that way.

What a postal code API actually returns

Response fields vary by provider and endpoint, but the core set is fairly consistent. A single-code lookup commonly returns:

Richer datasets add 90+ fields: boundaries, population, income, elevation, and more. You rarely need all of them — request only what your application uses.

A representative JSON response

{
  "postal_code": "90210",
  "city": "Beverly Hills",
  "state": "CA",
  "county": "Los Angeles",
  "latitude": 34.0901,
  "longitude": -118.4065,
  "timezone": "America/Los_Angeles",
  "area_codes": ["310", "424"]
}

XML responses carry the same information in tag form. Choose based on what your stack parses most easily; JSON is the common default.

Common request patterns

Most postal code APIs support four patterns. Knowing which one you need prevents wasted calls.

1. Lookup by code

You have a code and want its details. This is the simplest and fastest call.

GET /lookup?code=90210

2. Reverse lookup by address

You have a street address and want to confirm or complete the code. This is the pattern behind checkout address validation.

GET /validate?street=...&city=...&state=...

3. Radius search

You have a center point and want all codes within a distance. Useful for store locators and delivery zones.

GET /radius?code=90210&miles=10

4. Batch validation

You have a file of addresses and want them cleaned in bulk. Batch endpoints trade latency for throughput and usually have their own limits.

Handling missing and ambiguous matches

Real data is messy. Plan for these cases:

• No match — the code doesn't exist or the address is malformed. Return a clear error rather than a silent empty object.
• Multiple matches — a city name may map to several codes, or a code may span several acceptable city names. Decide whether to pick the primary or return a list.
• Partial match — the street is valid but the ZIP+4 isn't. Fall back to the 5-digit code.
• Stale data — codes are added, retired, and reassigned. Refresh your dataset on a regular schedule.

A practical rule: validate at the point of entry, store the normalized result, and never re-derive it later from raw user input.

Practical use cases

• Checkout address validation — catch typos before shipping, reduce failed deliveries.
• Shipping zone lookup — map a code to a zone, carrier route, or rate table.
• Data enrichment — append county, coordinates, or demographics to existing records.
• Store and service locators — radius search to find nearby branches or coverage areas.
• Territory and tax logic — county and boundary data drive jurisdiction rules.

Licensing and data-source considerations

Postal code data originates with national authorities — USPS in the United States and Canada Post in Canada. Providers license and repackage it, which is why accuracy, update frequency, and field coverage differ between services. Before committing:

• Confirm the data source and how often it refreshes.
• Check whether ZIP+4 and boundary data are included or sold separately.
• Review usage limits and whether batch processing is allowed.
• Read the license terms for redistribution and storage.

Pricing and plan details change, so check the provider's current documentation rather than relying on secondhand figures.

Getting started

1. Decide which request pattern you need (lookup, reverse, radius, or batch).
2. Pick the fields you'll actually store.
3. Write a small test call and inspect the raw response.
4. Add error handling for no-match and ambiguous cases.
5. Cache results where the same codes repeat.

A postal code API is ultimately a translation layer: you give it a code or an address, and it gives back structured location facts. Understand the fields, match them to your use case, and handle the messy edges — that's most of the work.

Compiler Explorer supports C++, Rust, Go, and many other languages, and for most of them you can choose among multiple compilers and compiler versions. The site is an interactive online compiler that shows the assembly output of your code, so the practical answer is: if a language has a compiler that can emit assembly or an intermediate representation, it is likely available. The exact list changes over time, so the authoritative source is the compiler dropdown on the site itself.

What the site states directly

The site description says Compiler Explorer is an interactive online compiler that shows the assembly output of compiled C++, Rust, Go (and many more) code. That confirms three named languages and explicitly leaves the list open-ended.

Languages visible in the interface

The page evidence lists output and analysis tools tied to specific toolchains, which indicates the breadth of support beyond the three named languages:

• C / C++ — the core use case, with assembly output, preprocessor, AST, LLVM IR, and optimization pipeline views.
• Rust — with Rust MIR, Rust HIR, and Rust macro expansion views.
• Go — listed in the site description.
• Haskell — GHC Core, GHC STG, and GHC Cmm views.
• Lean — a Lean C output view.
• Clojure — a Clojure macro expansion view.
• Solidity — a Yul (Solidity IR) view.
• Ada — GNAT debug tree and GNAT debug expanded code views.

This is not a complete list. It reflects the toolchains that have dedicated output panes in the interface, which is a subset of everything the site can compile.

Compilers and versions

For a given language, Compiler Explorer typically offers several compilers and several versions of each. The interface includes a version tree and a compiler selector, and the page evidence shows options such as "Clone Compiler," "Executor," and per-compiler argument fields. That means you can compare, for example, different GCC or Clang versions on the same C++ source, or switch between compilers for the same language.

How to check the current list

Because support is added and removed over time, verify against the live site rather than a static list:

1. Open Compiler Explorer.
2. Use the language selector to see the languages currently offered.
3. Use the compiler dropdown for that language to see available compilers and versions.
4. Add a second compiler pane if you want to compare outputs side by side.

The site also notes that without JavaScript the regular website is not functional, and points to a noscript version — relevant if you are checking support from a restricted environment.

Practical implications

• If you want to inspect generated assembly for C++, Rust, or Go, that is the site's core, well-supported path.
• If you work in Haskell, Lean, Clojure, Solidity, or Ada, dedicated intermediate-representation views exist, which suggests active support rather than incidental coverage.
• If your language is not listed, it may still be available; the interface list is the reliable check, not this summary.

Yes. The Compiler Explorer page shows no pricing, subscription, or payment requirement anywhere. It presents itself as an interactive online compiler that displays the assembly output of compiled C++, Rust, Go, and many other languages, and every feature visible on the page — compiling, sharing, embedding, and switching compilers — is offered without a paywall or login gate. The only money-related links are voluntary support options: Become a Patron, Sponsor on GitHub, Donate via PayPal, and a Compiler Explorer Shop.

What you can use without paying

The page evidence lists these capabilities as part of the normal interface:

• Compile and inspect output — compile to binary object, link to binary, or execute the code, and view output panes such as Preprocessor, AST, LLVM IR, Opt Pipeline, Control Flow Graph, and language-specific views like Rust MIR/HIR, GHC Core/STG/Cmm, and GNAT debug trees.
• Share results — Share Short Link, Full Link, and Embed in iframe.
• Save and reload — Hello Save/Load and Add new…, plus a History panel.
• Adjust the environment — Add tool…, Libraries, Overrides, compiler flags, stdin, and runtime tools.
• Work without JavaScript — the page states that without JavaScript the regular website is not functional, and links to a noscript version.

How to get started

1. Open compiler-explorer.com in a browser with JavaScript enabled (otherwise use the noscript version).
2. Pick a language and compiler in the left-hand pane.
3. Type or paste code into the Source Editor.
4. Press Compile (or Execute, if you want to run it) and read the assembly or other output on the right.
5. Use Share Short Link or Full Link to send the exact code, compiler, and flags to someone else, or Embed in iframe to place it in a page.

Expected result: you see the compiler's output for your code without creating an account or entering payment details.

Common snags

• Blank or broken interface — JavaScript is required for the regular site; switch to the noscript version if you cannot enable it.
• A tool is unavailable — the page notes "The current language or compiler does not support this tool," so some output panes only appear for certain language/compiler combinations.
• Output looks cluttered — use the Filters and Options controls (for example Demangle identifiers, Intel asm syntax, Hide Library Functions, Hide Debug Info) to reduce noise.

If you want to support it

Donations are optional and separate from usage. The page lists Patreon, GitHub Sponsors, PayPal, and a shop, along with a mailing list, wiki, and GitHub source for anyone who wants to contribute or follow development.

Compiler Explorer is an interactive online compiler that shows the assembly output of compiled C++, Rust, Go, and many other languages. You can use it to see exactly what a compiler does with your code: write source in the editor, pick a compiler and version, set flags, and read the generated assembly side by side with your input. Beyond that basic loop, it offers execution, binary output, optimization remarks, AST and IR views, and diff-style comparison of two compilations.

See the assembly your code compiles to

The core workflow is: type or paste code into the source editor, choose a language and compiler from the compiler selector, and the output pane updates with the generated assembly. The output pane has its own options, including Intel asm syntax, demangling of identifiers, verbose demangling, and filters for unused labels, library functions, directives, comments, and horizontal whitespace. You can wrap lines and select all output.

This is useful when you want to confirm whether a construct compiles to a single instruction, whether a loop was vectorized, or how a template or generic instantiation was resolved.

Switch compilers, versions, and flags

You can change the compiler and its version without leaving the page, and add compiler flags through the compiler options. A "Popular arguments" list and a "Detailed Compiler Flags" window are available for editing verbose flags. You can also add libraries and overrides, and clone a compiler or executor configuration.

Because the compiler version is selectable, you can check whether behavior changed between releases — for example, whether a newer version emits a tighter instruction sequence for the same source.

Execute the code and inspect binaries

The compiler output options include compiling to a binary object, linking to a binary, and executing the code. Execution has its own settings: compilation arguments, stdin, and runtime tools. This lets you test small programs end to end rather than only reading assembly.

Use the analysis and intermediate-representation views

The "Add tool" menu exposes many views beyond assembly, including:

Several of these have their own filters and options — for example, the LLVM IR view can demangle symbols, hide debug info and instruction metadata, and filter attribute groups, comments, declarations, and library functions. The optimization pipeline view can show missed, passed, and analysis optimization remarks, and can hide inconsequential passes.

Compare two compilations

A Diff View and a Tree (IDE Mode) layout are available, and the output area supports a left/right split with its own filters. Combined with the ability to open a new tab and keep history, this makes it practical to put two compilers, two versions, or two flag sets next to each other and read the differences directly.

Share and embed your setup

You can generate a short link or full link to your current code and configuration, embed the view in an iframe, and save or load state. Templates and a version tree are also provided. Note that the regular site requires JavaScript; a noscript version is linked for when JavaScript is unavailable.

Practical notes

• The interface includes a "Reset UI layout" and "Reset code and UI layout" option if you rearrange panes and want to start over.
• A "Conformance View" and "Compiler Execution Only" mode exist for narrower tasks.
• The site lists sponsors, a shop, a mailing list, a wiki, and a changelog, and states that the source is on GitHub — useful if you want to check how a feature works or report an issue.

If your goal is to understand what a specific compiler does with a specific piece of code, the shortest path is: paste the code, select the compiler and version, add the flags you care about, then read the assembly or open the IR/AST view that matches your question.