Notes from building ApyHub.
Engineering write-ups, product decisions, and the occasional opinion on how to ship developer infrastructure. Long enough to be useful, short enough that you'll finish it.
What Is a Webhook? How Webhooks Work, With Examples
A webhook is an HTTP request an app sends to your URL when something happens. How it works, webhook vs API, examples, and how to receive one safely.
What Is an API Endpoint? Definition, Examples and How It Works
An API endpoint is the URL where an API accepts a request for one task. See a real endpoint broken down, endpoint vs API vs route, and common errors.
Merge, Split and Compress PDFs from Your Code with One API Key
Merge, split, compress, rotate, watermark and redact PDFs with one API key. Send a file, get the finished PDF back in one request, with nothing stored.
Best Content Moderation APIs in 2026: Image, Video and Text Compared
Compare 7 content moderation APIs for images, video and text: OpenAI, Google, AWS, Azure, Hive, Sightengine and ApyHub. Free tiers, pricing and EU options.
OpenAI Decisions API Explained: How It Works and When Not to Use It
What the OpenAI Decisions API does, how it works, what it costs, and which decisions should be a simple rule or validation check instead.
PDF to Markdown with Python: A Resumable OCR Pipeline for RAG
Convert PDF to Markdown page by page with an OCR API, keep page numbers for citations and resume failed jobs. Python script for RAG ingestion.
Business Day Calculator in Python: Add Working Days with Holidays and Closures
Add business days that skip weekends, public holidays and company closures. Python tutorial with a working script, real response and boundary rules.
Invoice Generator API: Create Invoice PDFs from JSON with Python
Use an invoice generator API to turn billing records into PDF, Word or HTML invoices from JSON. Python tutorial with a working script and storage tips.
Text to Speech in Python: 5 Ways (Offline, Free and API)
Convert text to speech in Python with pyttsx3, Piper (offline), gTTS, edge-tts or a text to speech API. Short code examples and when to use which.
How to Save a Webpage as a PDF (Chrome, Safari, iPhone, Android and API)
Save any webpage as a PDF in Chrome, Edge, Firefox, Safari, iPhone and Android, fix pages that get cut off, and convert URLs to PDF automatically with an API.
REST vs GraphQL vs gRPC vs SOAP: API Protocols Explained
The main types of API protocols compared: REST, GraphQL, gRPC, SOAP, WebSockets, webhooks and MCP. What each one is, when to use it, with examples.
400 Bad Request Error: Causes and How to Fix It
What a 400 Bad Request error means, why it happens and how to fix it, in the browser and in your API. Includes the cookie too large fix and a debugging checklist.