PHP Baremetal
php-esp32 · v0.18.x
Docs · Recipes

Serve a web page

Serve an HTTP page straight from the board: run an HTTP server in front of PHP, hand each request to a fresh index.php with $_SERVER/$_GET/$_POST populated, and reach it at the board IP — from a hand-written page up to stock Laravel.

This recipe serves an HTTP page from the board itself. The firmware runs an HTTP server, and every request is handed to a fresh PHP run — the web-server execution model. You write the page; whatever you echo becomes the response body. The same model that serves a hand-written index.php also serves a stock Laravel app, so this page starts small and ends by pointing at the laravel-demo example.

What you need

  • A networked board. The web-server model needs a wired link, so pick a -ETH variant: ESP32-P4-ETH or ESP32-S3-ETH. A board with no network (a -Pico or -Zero) will not even offer web-server at init time.
  • A USB cable that carries data, for flashing and the serial console.
  • An Ethernet cable into the board's RJ45, on a network that hands out a DHCP address.

The web-server model in one paragraph

Each HTTP request is a fresh PHP request cycle, shared-nothing — exactly like a script behind Apache or PHP-FPM. The firmware turns the incoming request into a CGI-style environment ($_SERVER with method and URI, plus $_GET, $_POST, $_COOKIE), runs your entry script, and the status, headers, cookies and body it produces become the HTTP response. When the request ends, the engine tears userland down: variables, objects and resources are gone before the next request starts. Static files under a public/ root are served directly, without booting PHP. Because nothing you assign in one request survives into the next, state that must carry forward goes below userland — see the in-RAM store for mem_* and the run-once [web-server] init script.

A minimal example

Put this in project-src/index.php. It reads the request line out of $_SERVER, echoes an HTML page, and prints a fresh random number so you can see each request really re-executed rather than being cached.

php project-src/index.php 
<?php
// Runs fresh for every HTTP request, behind the firmware's HTTP server.
// You don't manage the socket or a loop: just produce the page, and
// whatever you echo becomes the response body.

$uri    = $_SERVER['REQUEST_URI']    ?? '/';
$method = $_SERVER['REQUEST_METHOD'] ?? 'GET';
$name   = $_GET['name'] ?? 'world';

echo "<!doctype html>\n";
echo "<html><head><meta charset=\"utf-8\"><title>PHP on ESP32</title></head>\n";
echo "<body style=\"font-family:sans-serif;max-width:34rem;margin:3rem auto\">\n";
echo "<h1>Hello, " . htmlspecialchars($name) . "</h1>\n";
echo "<p>Served fresh by PHP " . PHP_VERSION . " on an ESP32 microcontroller.</p>\n";
echo "<ul>\n";
echo "  <li>you requested: <code>" . htmlspecialchars("$method $uri") . "</code></li>\n";
echo "  <li>a fresh random number: " . random_int(1000, 9999) . "</li>\n";
echo "</ul>\n";
echo "</body></html>\n";

Add ?name=esp32 to the URL and the heading changes — that is $_GET populated per request. Always run untrusted input through htmlspecialchars() before echoing it into the page.

No counter in a hand-written page

Each request is a clean run, so there is no in-scope variable to count with. To keep a hit counter or any value across requests, write it to mem_* — the volatile in-RAM store that lives below userland. See the in-RAM store.

Running a real framework

The interesting part is that the same model serves an unmodified framework. The laravel-demo example is a stock composer create-project laravel/laravel (Laravel 13) with nothing edited: the board runs its front controller (public/index.php) per request, so routing, sessions, cookies and 404s are all real. GET / returns the full welcome page with Laravel's own headers and session cookies; GET /no-such-route returns Laravel's real 404; and static files under public/ are served directly, without booting the framework.

Three things make that work:

  1. 01

    `type = "web-server"`

    and entry = "public/index.php" — the HTTP server in front, pointed at the framework's front controller instead of a bare index.php.

  2. 02

    The framework's extension stack

    , all built into the firmware: mbstring (with onig for native mb_split), ctype, filter, tokenizer, session, openssl, sqlite and date. See the porting status.

  3. 03

    OPcache

    , enabled with [extensions.opcache]. Without it each request recompiles the whole framework, so a page takes on the order of 10–30 s; with the bytecode cache on the microSD it drops to a few seconds. The laravel-demo-optimized example turns it on.

The whole app — including vendor/ (~30 MB) — is far too big for the embedded image, so it lives on the microSD: you copy the contents of project-src/ to the card root yourself, and the firmware serves it from there. See the example's own README for the card-prep steps (composer install, php artisan key:generate).

Frameworks need the P4's PSRAM

A full framework leaves ~33 MB of PSRAM free on the ESP32-P4-ETH (up to 32 MB PSRAM) — plenty. The ESP32-S3-ETH has only 8 MB of PSRAM, which is tight: it runs the hand-written page and lighter apps fine, but a stock Laravel or Symfony can run out of memory mid-request. Use a P4 for the frameworks.

Config

A minimal web-server project on the networked P4 board. For the hand-written page the entry is a bare index.php; for a framework, point entry at public/index.php and enable the framework's extensions plus opcache.

toml php-esp32.config.toml — minimal web-server 
name = "web-page"
storage_type = "microsd"   # where the PHP source lives
type = "web-server"        # HTTP server in front, PHP per request

[board]
target = "esp32-p4-eth"    # a networked board -- web-server needs the wired link
port   = ""                # empty = autodetect at flash time

[esp-idf]
path    = ""
version = ""

[php-esp32]
path    = ""
version = ""

[php]
src   = "project-src"      # PHP source folder (copied to the microSD)
entry = "index.php"        # bare page; a framework sets public/index.php

To seed data or bring hardware up once before the server starts, add a [web-server] init script — it runs a single time at boot with its output going to the serial console. See the in-RAM store for the paired init + mem_* pattern.

Build & flash

Build the firmware, write it to the board, then open the serial monitor.

bash build, flash, monitor 
phpflash build && phpflash flash && phpflash monitor

With storage_type = "microsd" the PHP source is read from the card at boot, so to change the page you copy project-src/ to the card root and press reset — no rebuild. If OPcache has already cached the old code, clear the cache folder on the card too so the board recompiles.

What you'll see

The board brings the Ethernet link up, gets a DHCP address, and prints it on the serial log. That line is where you point a browser or curl.

text serial output (excerpt) 
php-esp32: microSD mounted at /sdcard
network up -- http://192.168.1.42/
web-server model: serving /sdcard/index.php over HTTP on :80

Open that address in a browser, or hit it with curl:

bash terminal — request the board 
curl -i http://192.168.1.42/
curl "http://192.168.1.42/?name=esp32"

-i shows the status line and headers; refresh a few times and the random number changes, confirming each request is a fresh PHP run.

Next

For an app that stores data, continue to Query SQLite with PDO. To keep a counter or a small cache across requests without touching flash, use the in-RAM store. To run a full framework end to end, copy the laravel-demo (or laravel-demo-optimized, with OPcache) example and follow its README.

Last updated · 2026-08-31
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