COURSES + FIELD NOTES 12 courses · 8 disciplines EST. 2024

From a first script to a service in production.

WPSifero publishes courses and technical writing about programming. Five language courses — Python, JavaScript and TypeScript, PHP, SQL and Go — run from your first program to the parts you only meet under real traffic. Five more go deep into WordPress and WooCommerce, because that is where the two hardest things in this trade meet: a codebase you did not write, and a database under load.

Every course is text. No video, nothing to scrub through, nothing to re-watch at half speed. You read a lesson, type the code yourself, and finish with something that runs.

Browse the courses Read the articles

Curriculum status

$ wpsifero --curriculum

[ OK ]Go 1.24+18/18

[ OK ]Node 22 LTS+18/18

[ OK ]PHP 8.3+18/18

[ OK ]Python 3.12+18/18

[ OK ]MySQL · PostgreSQL · SQLite18/18

[ OK ]WordPress 7.0 · WooCommerce 11.218/18

[ OK ]WooCommerce 11.218/18

[ OK ]WordPress 7.018/18

[ OK ]WordPress 7.0 · PHP 8.5 · Claude Code · Codex · OpenCode18/18

[ OK ]WordPress 7.0 · Redis18/18

[ OK ]WordPress 7.018/18

[ OK ]WordPress 7.0 · PHP 8.3+18/18

$ _

Courses: 12
Lessons: 216
Articles: 085
Reading time: 131H 39M

01 Sector map

What you will find here

Three shelves: the languages, the platform, and the disciplines that apply to all of it.

LANG

The languages

Five courses, each running from your first program to the parts that only show up in production. Text, with a lab and a worked solution in every lesson.

Open the language courses

WP

WordPress and WooCommerce

The platform that runs a large share of the web, written against WordPress 7.0 and WooCommerce 11.2 rather than against tutorials from three versions ago.

Open the WordPress courses

DISC

The disciplines

The subjects that do not care which language you write: query budgets, cache invalidation, REST contracts, capability checks, accessibility, tooling.

Browse the articles

01 Lead transmission

This month's deep dive

Long-form work where the measurement matters more than the opinion.

Topic: WOO
Section: WooCommerce & Storefront
Published: 06 OCT 2026
Reading time: 7 MIN
Words: 1977W

Building Order Tracking in WooCommerce Without a Tracking Subscription

Most post-purchase support tickets are "where is my order". Here is the plugin architecture that answers them without shipping customer data to a tracking service.

Ana Ferreiro · @aferreiro

WooCommerce engineering

Covers the WooCommerce order lifecycle: checkout, HPOS, session handling, transactional email and the post-purchase layer where most storefront complaints actually originate.

Read the full analysis

02 Curriculum

Courses you read, not watch

12 complete text courses, 216 lessons, no video. Written to be read at your own pace and typed out rather than copied.

DEV05 COURSES

Programming track

Language and platform courses that start at a first script and end at the parts you only meet in production.

Go for Backend Services18 lessons · 10H 30M
JavaScript and TypeScript, from Script to Application18 lessons · 10H 15M
Modern PHP, from Syntax to Services18 lessons · 9H 21M
Python from First Script to Service18 lessons · 9H 25M
SQL and Relational Database Design18 lessons · 11H 10M

WP07 COURSES

WordPress track

Courses built against WordPress 7.0 and WooCommerce 11.2, covering plugin and block development through to performance and security.

Building the Sifero Courier Timeline Plugin18 lessons · 8H 50M
WooCommerce Extension Development18 lessons · 10H 35M
WordPress Block Themes and Full Site Editing18 lessons · 10H 00M
WordPress Development with AI Agents18 lessons · 10H 15M
WordPress Performance and Scaling18 lessons · 10H 25M
WordPress Plugin Development18 lessons · 8H 45M
WordPress Security and Hardening18 lessons · 10H 45M

Open the course catalogue How this material is written

02 Transmission log

Latest articles

Newest first. Every entry is tagged by discipline and carries an estimated reading time.

001 Triaging a WooCommerce Checkout That Dies at Payment A pending order and a request that died before the order existed need different recovery. Here is how to tell which one you are looking at. WOO Ana Ferreiro 16 OCT 2026 · 8M 002 The White Screen of Death, and How to Read It A blank page is a fatal error with nowhere to print. Where the log lives on four host types, and how to bisect plugins without showing errors to visitors. WP Martin Kiel 16 OCT 2026 · 7M 003 Multisite Uploads, Domain Mapping and the Traps Nobody Documents Cron runs once per site, uploads get a suffix per blog ID, and domain mapping rewrites home and siteurl without moving the upload URL with them. INFRA Martin Kiel 16 OCT 2026 · 8M 004 “Allowed Memory Size Exhausted” Is Almost Never a Memory Problem The fatal names the file that ran out, not the code that filled memory. How to find the query or loop that is actually growing in memory. PERF Martin Kiel 16 OCT 2026 · 8M 005 “Error Establishing a Database Connection”, Diagnosed Properly Five faults print one sentence, and it names none of them. A one-minute probe that tells credentials, host, a dead server, a full disk and a bad table apart. INFRA Martin Kiel 16 OCT 2026 · 8M 006 WP-Cron Is Not Broken, You Just Have No Traffic The scheduler runs on page views, so a quiet site runs nothing. A reproduction of a missed event, the DISABLE_WP_CRON trap, and the cron entry that fixes it. INFRA Martin Kiel 16 OCT 2026 · 8M 007 Blocks That Break After an Update, and Why save() Is the Reason A save() function whose output changes without a matching deprecated entry makes the editor call the block invalid. Here is the reproduction and the fix. WP Devon Parker 16 OCT 2026 · 8M 008 Why Your WordPress Site Is Slow, and Which Part Is the Host Five things make a WordPress site feel slow, and hosting is only one of them. Measure TTFB, query count, image weight and the waterfall before you spend. PERF Priya Raghunathan 16 OCT 2026 · 9M 009 What to Check Before You Buy WordPress Hosting A buying checklist for WordPress hosting, built around the number most comparisons hide: what the plan costs in year two, not year one. INFRA Priya Raghunathan 16 OCT 2026 · 8M

Open the complete index (85 articles)

04 Sector map

Topics

Eight disciplines, each with its own archive and its own set of recurring failure modes.

WP17

WordPress Internals

Hooks, the database layer, cron, and the parts of core that decide how your plugin behaves under load.

WOO08

WooCommerce & Storefront

Order lifecycle, checkout, HPOS, sessions and the post-purchase communication layer.

PERF10

Performance

Query budgets, object caching, Core Web Vitals and measuring before you optimise.

API06

APIs & Integrations

REST design, webhooks, authentication, idempotency and talking to couriers and ERPs.

SEC08

Security & Hardening

Capability checks, nonces, sanitisation, SQL safety and threat modelling for plugins.

FE14

Frontend & Accessibility

Block themes, progressive enhancement, ARIA, and interfaces that work without JavaScript.

TOOL08

Tooling & Workflow

Local environments, static analysis, CI, release packaging and debugging technique.

INFRA14

Hosting & Infrastructure

Server configuration, caching layers, queues, observability and deployment practice.

05 Operating principle

What we publish, and what we refuse to

This section exists so readers and reviewers can hold us to a stated standard.

Every claim is reproducible

Performance numbers come from a stated environment. We publish the query count, the cache state and the sample size, because a benchmark without its conditions is an advertisement rather than a measurement.

Disagreement is documented

Where a recommended pattern has a cost, that cost appears in the same article rather than a follow-up. If an approach fails past a certain order volume, we say at which volume it fails.

No undisclosed interests

WPSifero maintains its own plugins. Whenever an article touches a product we build, the relationship is disclosed inside that article, at the top, in plain language.

Read the full editorial standards