> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pictify.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Glossary

> Key terms and definitions

# Glossary

A reference guide to terms used throughout the Pictify documentation.

## A

### API Key

A secret token used to authenticate requests to the Pictify API, passed as a Bearer token. New keys are `pic_live_` followed by 64 hex characters; older bare-hex keys remain valid. Every key is live; there is no separate test-key type.

### Agent Screenshot

An AI-powered feature that uses natural language prompts to navigate to a webpage and capture specific content automatically.

## B

### Batch Operation

Processing multiple renders in a single API request. More efficient than individual requests for generating many images.

### Binding

A connection between a template and an external data source that automatically refreshes the rendered image when data changes.

## C

### Canvas Rendering

Generating images from FabricJS canvas JSON data, enabling programmatic image creation with objects, text, and shapes.

### CDN (Content Delivery Network)

A globally distributed network that serves rendered images from locations close to users for faster loading.

## D

### Device Scale Factor

A multiplier for output resolution. A factor of 2 produces "retina" images at 2x the specified dimensions.

## E

### Expression

Dynamic code within templates using `{{...}}` syntax. Supports variables, operators, and built-in functions.

### Expression Engine

The system that evaluates expressions in templates, providing features like string formatting, math operations, and conditionals.

## F

### FabricJS

An open-source JavaScript canvas library. Pictify can render FabricJS canvas JSON directly to images.

## G

### GIF Capture

Recording an animated GIF from a live webpage, capturing CSS animations or JavaScript-driven motion.

## H

### HMAC-SHA256

The cryptographic algorithm used to sign webhooks, ensuring they originate from Pictify and haven't been tampered with.

### HTML Rendering

Converting HTML and CSS code into image formats like PNG, JPEG, or WebP.

## I

### Idempotency

The ability to safely retry requests without duplicate effects. Enabled by the `Idempotency-Key` header.

### Idempotency Key

A unique identifier included in requests to ensure they're only processed once, even if sent multiple times.

## M

### MCP (Model Context Protocol)

A standard protocol for connecting AI models to external tools. Pictify's MCP server enables AI agents to generate images.

## O

### OG Image (Open Graph Image)

The preview image shown when content is shared on social media platforms like Facebook, Twitter, and LinkedIn.

### OpenAPI

A specification for documenting REST APIs. Pictify provides an OpenAPI 3.1 spec for API reference.

## P

### PDF Preset

Standard paper sizes for PDF generation (A4, Letter, Legal, etc.) with predefined dimensions.

### Problem Details (RFC 9457)

A standard format for API error responses that includes type, title, status, and detail fields.

## R

### Rate Limit

Restrictions on how many API requests can be made in a time period. Varies by plan (Free: 60/min, Pro: 300/min, etc.).

### Render

The process of converting templates, HTML, or URLs into images, GIFs, or PDFs.

### Retina Image

A high-resolution image (typically 2x or 3x) optimized for high-DPI displays like Apple Retina screens.

### RFC 9457

The IETF standard for "Problem Details for HTTP APIs" used by Pictify's error responses.

## S

### Selector

A CSS selector used to capture a specific element on a page rather than the full viewport.

### Signing Secret

A cryptographic secret used to verify webhook signatures. Unique to each webhook subscription.

### SSRF (Server-Side Request Forgery)

A security vulnerability where attackers trick servers into making unintended requests. Pictify blocks private network URLs to prevent SSRF.

## T

### Template

A reusable design with variable placeholders that can be rendered with different data.

### Template Variable

A placeholder in a template (like `{{title}}`) that gets replaced with actual data during rendering.

### Tool Schema

JSON schema definitions for AI tool integration, describing available functions and their parameters.

### Transparent Background

PNG or WebP images with alpha channel transparency instead of a solid background.

## U

### User Storage

Optional cloud storage (S3, R2, etc.) where Pictify can upload rendered images in addition to the CDN.

## V

### Variable Interpolation

The process of replacing template placeholders (`{{variable}}`) with actual values during rendering.

### Variable Set

A collection of variable values used to render a template. Batch operations accept arrays of variable sets.

## W

### Webhook

An HTTP callback that notifies your server when events occur (render completed, batch finished, etc.).

### Webhook Signature

A cryptographic signature in the `X-Pictify-Signature` header used to verify webhook authenticity.

### WebP

A modern image format developed by Google offering better compression than PNG or JPEG while supporting transparency.

## Common Abbreviations

| Abbreviation | Full Term |
| - | - |
| API | Application Programming Interface |
| CDN | Content Delivery Network |
| CSS | Cascading Style Sheets |
| DPI | Dots Per Inch |
| GIF | Graphics Interchange Format |
| HMAC | Hash-based Message Authentication Code |
| HTML | HyperText Markup Language |
| HTTP | HyperText Transfer Protocol |
| JSON | JavaScript Object Notation |
| JWT | JSON Web Token |
| MCP | Model Context Protocol |
| OG | Open Graph |
| PDF | Portable Document Format |
| PNG | Portable Network Graphics |
| REST | Representational State Transfer |
| SDK | Software Development Kit |
| SSRF | Server-Side Request Forgery |
| URL | Uniform Resource Locator |
| UTC | Coordinated Universal Time |


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