onecompiler.com

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.

OneCompiler's own site says the editor is "Free to use, in 110+ languages," and its homepage states it helps over 12.8 million users write code online. At the same time, the site navigation includes a Pricing link (onecompiler.com/pricing), which indicates paid plans exist alongside the free offering. The homepage does not spell out what the paid tiers include, so the free-vs-paid feature split can only be confirmed on the pricing page itself.

What the free tier covers

Based on the homepage evidence, the free offering is centered on the browser editor:

• Code online with One Compiler — the editor runs in the browser with no install mentioned ("Nothing to install. Open the editor").
• 110+ languages and databases — the site advertises support for over 110 languages and databases, with popular options listed such as Python, JavaScript, Java, C, C++, C#, PHP, HTML, MySQL, MongoDB, PostgreSQL, NodeJS, React, FastAPI, Lua, PL/SQL, Spring Boot, and Pygame.
• AI coding agent in the browser — the editor includes an agent that reads your workspace, edits files in place, creates new files, and cleans up after itself, with every change landing behind a checkpoint you can roll back.

The homepage does not state any usage caps, login requirements, or feature gates on these items, so treat "free" as the advertised default rather than a confirmed unlimited tier.

What the Pricing link suggests

The presence of a dedicated Pricing page is the clearest signal that OneCompiler has a commercial side. The homepage also points to business-oriented capabilities that commonly sit behind paid plans:

• Embedding — you can embed the editor and challenges as an iFrame into your website to get code execution capabilities "in minutes."
• APIs to run code — call APIs from backend applications to run code and read reports.
• Custom workflows — reach out to build workflows not covered by the APIs.
• Trusted by 100+ customers — the site notes that 100+ customers across the globe trust it, which points to a customer/business tier rather than only individual free use.

None of these sections list a price, a free quota, or a paid-only restriction on the homepage. To know whether embedding, API access, or custom workflows require payment, you have to check the Pricing page.

How to decide

Practical next step

Open onecompiler.com/pricing and compare it against the free editor before committing to either path. If your use case is individual coding practice or quick experiments, the free editor as described on the homepage is likely enough. If you need embedding, API calls, or custom workflows for a product, confirm the plan and limits on the pricing page first, since the homepage only confirms that these capabilities exist — not what they cost.

OneCompiler supports 110+ languages and databases, so the practical answer is that most common languages and several major databases are covered. The site lists Python, JavaScript, Java, C, C++, PHP, and C# among its popular programming options, plus MySQL, MongoDB, and PostgreSQL among databases. It also names HTML, React, NodeJS, Spring Boot, FastAPI, Lua, PL/SQL, and Pygame as supported options. If your language is not in that visible list, the "110+" figure means it may still be available — check the language selector in the editor.

Programming languages

The homepage groups these under "Popular Programming":

Additional languages and frameworks named on the page:

• HTML
• React
• NodeJS
• Spring Boot
• FastAPI
• Lua
• PL/SQL
• Pygame

Databases

The page lists these under "Web Databases":

• MySQL
• MongoDB
• PostgreSQL

How to confirm your specific language

The homepage only surfaces a subset of the 110+ options. To verify a specific language or database:

1. Open the OneCompiler editor.
2. Look for the language or database selector (the page shows a language list alongside the editor).
3. Search or scan for your target language.
4. If it appears, you can write and run code directly in the browser.

Expected result: your chosen language loads in the editor and the Run control becomes available. If it does not appear in the selector, it is likely not supported despite the 110+ total.

What else runs alongside the languages

The page also describes an in-browser coding agent that reads your workspace, edits files in place, creates new ones, and cleans up after itself. Changes land behind checkpoints you can roll back, and the page states there is nothing to install. This is separate from language support but relevant if you plan to use OneCompiler for multi-file projects rather than single snippets.

Practical selection guidance

• If you need a mainstream language (Python, JavaScript, Java, C, C++, PHP, C#), it is explicitly listed.
• If you need a relational or document database (MySQL, PostgreSQL, MongoDB), those are explicitly listed.
• If you need a web framework (React, NodeJS, Spring Boot, FastAPI), those are named.
• If your language is niche, treat the 110+ claim as a starting point and confirm in the editor before relying on it.

The page does not list every one of the 110+ languages individually, so the visible list is a sample rather than an exhaustive inventory.

Yes. OneCompiler offers three integration paths for embedding code execution into your own product: an iFrame embed of its editor and challenges, APIs for running code and reading reports from your backend, and custom workflows built on request for use cases the APIs don't cover. The iFrame route is the fastest to ship; the API route is for backend-driven execution; custom workflows are for anything outside both. OneCompiler states that 100+ customers already use these integration capabilities.

The three integration options

The iFrame option is described as the low-effort path: drop the embed in and you inherit the editor and execution rather than building them. The API option is framed around more complex use cases — running code and reading reports from your own backend. Custom workflows exist precisely because the API set is finite; if your requirement falls outside it, the documented next step is to reach out rather than work around it.

What the editor embed actually gives you

The embed isn't only a text box. OneCompiler's editor includes a coding agent that reads your workspace, edits files in place, creates new ones, and cleans up after itself step by step while the user watches. Every change lands behind a checkpoint that can be rolled back, and nothing needs to be installed.

Concretely, in the product's own example, a user asks for a dark mode toggle that remembers the choice. The agent reads the header markup and existing styles, edits index.html and styles.css, and creates script.js — then reports that the button is in place, the styles switch on a dark class, and the script saves the choice in localStorage so it persists on refresh. The turn is summarized as 4 steps, 3 files changed (+41 −6), 2.8k tokens, 5.4s, with Restore, Reject, and Apply controls.

If you embed the editor, that agent behavior is part of what your users get. If you only call the APIs, you're using execution and reporting, not the agent UI.

Choosing between the embed and the API

Use the iFrame embed when the code editor should be visible and interactive — for example, a tutorial site where readers edit and run snippets inline, or a challenge page where they submit solutions. The stated benefit is speed: execution capabilities in minutes, with no execution infrastructure of your own.

Use the APIs when execution is a backend concern. Typical shapes: your application submits code and needs the result, or you need to read reports rather than show an editor. This keeps your own interface in control and avoids exposing an embedded editor you don't want.

Consider custom workflows only after checking the API documentation and finding your requirement missing — for instance, if you need execution wired into a pipeline the standard endpoints don't model.

Practical checks before you commit

• Read the API documentation first. OneCompiler links to it directly from the integrations section; the API surface defines what you can build without a custom engagement.
• Confirm the embed fits your page. The editor and challenges are embedded as an iFrame, so plan for the frame's size and how it sits in your layout.
• Decide whether you want the agent. The in-editor agent edits files and creates checkpoints. That's valuable for interactive learning products and unnecessary overhead if you only need headless execution.
• Check the language and database coverage against your use case. OneCompiler advertises 110+ languages and databases, with popular entries including Python, JavaScript, Java, C, C++, PHP, C#, HTML, and MySQL, plus newer additions such as FastAPI, Lua, PL/SQL, NodeJS, MongoDB, Spring Boot, React, PostgreSQL, and Pygame. If your stack isn't listed, that's a question for the custom-workflow conversation.
• Ask about pricing for your volume. OneCompiler publishes a pricing page, but the integration terms for embeds, API calls, and custom workflows aren't specified in the material here — treat cost as something to confirm directly rather than assume.

Bottom line

If you want a working code editor on your site quickly, the iFrame embed is the intended path. If you want execution driven by your own backend, use the APIs. If neither fits, custom workflows are the documented escape hatch. In all three cases, the API documentation and a direct conversation about your specific use case are the next steps — the published material describes the capabilities but not the commercial terms.

OneCompiler is a browser-based online compiler and coding environment where you can write, run, and share code without installing anything locally. It supports 110+ programming languages and databases, and its editor page states it is free to use. It fits quick experiments, learning a language, sharing runnable snippets, and embedding code execution into your own site or backend. If you need a full local toolchain, private repositories, or offline work, it is not a replacement for a desktop IDE.

What OneCompiler actually is

OneCompiler is a hosted service that runs your code on its servers and returns the output in your browser. You open the editor, pick a language, type code, and press Run. There is nothing to install, and the same page lets you share what you wrote.

The site reports it helps over 12.8 million users worldwide, and that users come from major companies and schools. Those numbers describe scale, not a guarantee about any specific language or runtime version.

What you can do with it

Write and run code in 110+ languages

The homepage lists popular choices including Python, JavaScript, Java, C, C++, PHP, C#, HTML, and databases such as MySQL, MongoDB, PostgreSQL, and PL/SQL. Newer additions shown include FastAPI, Lua, NodeJS, Spring Boot, React, and Pygame.

A typical loop looks like this:

1. Open the editor and select a language or stack.
2. Type or paste your code into the editor pane.
3. Run it and read the output in the results pane.
4. Adjust and re-run, or share the link.

The expected result is immediate feedback on whether the code compiles and what it prints — useful for checking syntax, testing a small function, or trying a library call.

Share runnable code

Because the environment lives at a URL, you can send a link instead of pasting a code block into a chat or issue. The other person sees the same code and can run it themselves. This is the main reason people use it for teaching, code review questions, and bug reports.

Embed the editor in your own site

OneCompiler offers editor and challenge embedding: you can drop its editor into your website as an iFrame and get code execution capability "in minutes." This suits documentation sites, course platforms, and tutorial pages that want a live example rather than a static snippet.

Call its APIs from your backend

Beyond the browser, you can call OneCompiler's APIs from backend applications to run code and read reports. If your use case is not covered by the APIs, the site says you can reach out to build custom workflows. Start from the API documentation linked on the homepage.

Use the in-browser coding agent

The editor includes an AI agent that reads your workspace, edits files in place, creates new ones, and cleans up after itself, step by step, while you watch. Each turn is a checkpoint you can restore or re-apply, and changed lines are marked as they stream into the editor.

The homepage shows a worked example: the instruction "Add a dark mode toggle to the header and remember the choice" produced edits to index.html and styles.css and a new script.js, with the summary noting the toggle button, a dark class in CSS, and a localStorage save so the choice persists on refresh. The run reported 4 steps, 3 files changed (+41 −6), 2.8k tokens, and 5.4s. Treat those figures as one example, not a benchmark — your results depend on the task and the model selected.

Who it is for

Practical things to check before relying on it

• Language and version: confirm your language is in the supported list and that the runtime behaves like the one you deploy to.
• Secrets: anything you paste into a shared snippet is visible to whoever has the link. Keep API keys and credentials out.
• Persistence: the agent's checkpoints let you roll back within a session, but do not assume your workspace is a permanent backup. Keep real projects in your own repository.
• Pricing and limits: the editor page says "Free to use, in 110+ languages," and a Pricing page exists. If you plan to embed the editor, call the APIs at volume, or need custom workflows, check the Pricing page and API documentation for the terms that apply to your usage rather than assuming the free tier covers it.

The fastest way to judge it is to open the editor, run a small program in the language you care about, and try one embed or API call if that is your actual use case.