# RenderStack Features

## Visual Template Editor

Drag-and-drop canvas editor for designing image and PDF templates. Supports text, images, rectangles, ellipses, lines, SVGs, and QR codes. Every element can be positioned precisely with pixel-level control over typography, spacing, fill, stroke, corner radius, rotation, and opacity. Convert any element to a different type at any time using the Type dropdown in the Properties panel — for example, change a text frame to an image frame or a rectangle to an ellipse. Compatible properties carry over automatically during conversion.

## Dynamic Layers

Mark any element as dynamic with an API name. When rendering, pass data overrides for text content, image sources, colors, visibility, and more. The template defines the layout; the API provides the data.

## REST API Rendering

Generate images programmatically via sync (`POST /api/v1/renders/sync`) or async (`POST /api/v1/renders`) endpoints. Override any layer with custom data per render. Supports PNG, JPEG, and multi-page PDF output with configurable quality and dimensions.

## Dynamic Image URLs (GET Endpoint)

Generate images via GET request with query parameters (`GET /api/v1/render?template=...&key=...&title.text=Hello`). Embed directly in HTML img tags — no server-side code required. Supports dot-notation layer overrides, built-in caching, rate limiting, and allowed host access controls.

## Auto-Layout Containers

Flexbox-powered containers that automatically reflow child elements when content changes size or visibility. When an element hides due to missing data, remaining elements reposition automatically — no manual layout fixes needed.

## Fallback Chains

Declare ordered fallback strategies for each dynamic layer. If API data is missing, fall back to initials, then a default value, or hide the element entirely. All fallback logic is defined in the template — zero client-side handling required.

## Repeater Elements (Business & Enterprise Plans Only)

Render variable numbers of items from a single template. Define a repeater container with one item layout, then send an array of data via the API. RenderStack clones, positions, and renders 1 to N items automatically. Available on Business and Enterprise plans. Row template child layers are bound by `apiName` within each data item object. Supports vertical, horizontal, and grid layouts with configurable gaps, item caps, and auto-sizing. See [Repeater Elements guide](/docs/repeater-elements) for more details.

## Conditional Visibility Rules

Show or hide elements based on data presence, value conditions, or group logic. Combine with auto-layout containers for templates that adapt their structure based on the data provided.

## Non-Blocking Renders

If an asset fails to load (broken image URL, invalid QR data), the render continues with warnings instead of failing. Detailed error information is returned in response headers and render history.

## QR Code Elements

Add QR codes to templates with dynamic data. Pass the URL or content string as an API override at render time. Configurable size, position, and error correction level.

## AI Template Creation

Upload a PNG, JPG, WebP, or PDF file and AI vision analyzes the layout. It detects text blocks, image regions, shapes, and spatial relationships, then generates an editable template with properly positioned elements. Refine in the editor and start rendering immediately.

## Rich Text & Inline Styling

Style individual words and characters differently within a single text frame using the textRuns system. Apply bold, italic, underline, strikethrough, color, highlight, font family, font size, superscript, and subscript to specific words or characters — all within one text element. Three input methods: structured textRuns array via API, Markdown-like richText shorthand (supports **bold**, *italic*, __underline__, ~~strikethrough~~, {color:#hex}, {hl:#hex}, {sup}, {sub}, {font:Name}), or plain text. Priority: textRuns > richText > text. Supports pharmaceutical dosage notations (mg/m²), trademark symbols (™, ®), chemical formulas (H₂O), footnote markers, and mixed formatting for regulated industries. Edit inline on-canvas with a floating toolbar or use the properties panel Visual/Markdown modes.

## Custom Fonts

Upload font files in TTF, OTF, WOFF, or WOFF2 format through the asset manager. All formats are fully supported in both the visual editor and the server-side rendering engine for exact brand typography control.

## Asset Management

Upload and organize images and fonts. Searchable asset library with instant preview. Use assets across any template in your organization.

## API Key Management

Create keys with four permission levels: master (full access), project (template-scoped), read-only (view only), and GET (dynamic URL embedding only). Revoke or delete keys with full audit trail.

## URL Builder

Interactive tool to construct and test dynamic image URLs without writing code. Select a template, enter layer overrides, preview the result, and copy the URL for embedding.

## AWS S3 Integration

Auto-upload rendered images to your own S3 bucket. Configure credentials once (encrypted with AES-256-GCM at rest), toggle per render request. Non-blocking — renders succeed even if upload fails.

## Multi-Tenancy and Team Collaboration

Create organizations, invite team members with roles (owner, admin, user, viewer). All data is isolated per organization with role-based access control enforced across every feature.

## Activity Log

Filterable, searchable log of every platform event — renders, API key actions, template changes, authentication events, and security events. 90-day retention with structured metadata.

## Analytics Dashboard

At-a-glance overview of total templates, renders, success rates, average render duration, and recent activity feed.

## AI Assistant

Built-in conversational AI that understands your templates, renders, assets, API keys, and settings. Ask natural-language questions and get answers with source citations.

## Rendering Defaults

Configure default output format (PNG, JPEG, PDF), JPEG quality (1-100), and pixel density. Apply globally or override per render request.

## Outbound Webhooks

Receive real-time HTTPS notifications when important events happen — renders completing, templates changing, team membership updates, usage limits approaching, and more. Configure endpoints per organization with HMAC-SHA256 signed payloads, automatic retries with exponential backoff, and a delivery log with 30-day retention. Test endpoints before going live and rotate signing secrets when needed.

## Email Notifications

Stay informed with automatic email alerts for billing events, trial milestones, usage warnings, and team activity. Control exactly which notifications you receive from your profile preferences, and unsubscribe from any category with one click. Organization owners receive critical alerts about payment failures and account status changes so issues can be resolved quickly.

## Smart Cover (AI Focal Crop)

AI-powered image positioning that detects faces and key subjects in images, then aligns them to a designer-specified focal point within the frame. Prevents subjects from being cropped out when image frames are partially covered by overlapping content. Specify exact X% and Y% coordinates to position subjects precisely where you need them (defaults to center-center). Supports pre-analysis for uploaded assets and pre-computed coordinates via API.

## Image Caching & CDN Optimization

Built-in server-side caching for images rendered via the GET endpoint. Repeated requests with the same parameters return cached results instantly without re-rendering. Response headers (`X-Cache: HIT`/`MISS`) indicate cache status. Cache TTL is configurable per plan, and Enterprise customers can customize cache settings via self-service controls in Settings. Purge cached images via API — by individual cache key, by template, or for the entire organization. Template edits automatically invalidate associated cache entries. Compatible with CDN layers like Cloudflare and CloudFront for edge caching and global performance. Cache usage and hit rate analytics available on the Billing page.

## Security Features

- Scoped API keys with four permission levels
- Allowed hosts: restrict GET URL access to specific domains, wildcards, IPs, or CIDR ranges
- Rate limiting: sliding window per key and per IP
- AES-256-GCM encrypted AWS and webhook credentials
- HMAC-SHA256 signed webhook payloads with SSRF protection
- Full audit trail via activity log