# RenderStack FAQ

## How do I generate images from a template using an API?

RenderStack lets you design image templates in a visual drag-and-drop editor, mark any element as dynamic, then call a REST API with your custom data to generate unique images on demand. Send a POST request with JSON overrides for text, images, colors, and visibility — and get back a pixel-perfect PNG, JPEG, or PDF. No browser or canvas runtime needed on your end.

## Can I generate dynamic Open Graph (OG) images and social cards automatically?

Yes. Design your OG image template once in the visual editor, then generate unique social cards per page by calling the API or embedding a GET URL directly in your meta tags. RenderStack supports dynamic text, images, QR codes, and conditional visibility — so every page gets a unique, on-brand social preview without manual design work.

## What is the best alternative to Bannerbear, Placid, or HTMLcsstoimage for developers?

RenderStack is built API-first for developers who need more than basic image stamping. Unlike alternatives, it includes auto-layout containers that reflow content automatically, fallback chains for missing data, repeater elements for variable-count items, and conditional visibility rules — all handled server-side. You design visually but render programmatically with full deterministic control.

## How do I generate personalized certificates, invoices, or PDF documents at scale?

Design your certificate or invoice layout in the RenderStack visual editor, mark fields like name, date, amount, and QR code as dynamic layers, then call the render API with each recipient's data. RenderStack outputs PNG, JPEG, or multi-page PDF. Repeater elements handle line items, and auto-layout containers reflow content when item counts change.

## Can I use RenderStack with Webflow, WordPress, or no-code tools?

Absolutely. RenderStack provides embeddable GET URLs that you can paste directly into any HTML img tag — no server-side code required. Use the built-in URL Builder to construct the URL visually, set your overrides via query parameters (dot-notation supported), and embed the image URL in Webflow, WordPress, email templates, or any platform that supports HTML. GET API keys are scoped for safe client-side use.

## How does dynamic image URL embedding work without writing backend code?

RenderStack's GET endpoint lets you render images via a URL with query parameters. Add your template slug, a GET-scoped API key, and layer overrides using dot-notation (e.g., title.text=Hello&title.fill=%23ff0000) directly in an img src attribute. Built-in caching, rate limiting, and allowed-host restrictions keep it secure. The URL Builder tool lets you construct and preview these URLs without writing any code.

## Can I generate images programmatically from a Cursor, Bolt, Lovable, or Replit vibe coding project?

Yes. RenderStack's REST API works with any language, framework, or AI-assisted coding tool. Whether you're building with Cursor, Bolt, Lovable, or Replit, you just make an HTTP POST with JSON data and get back an image or PDF. The API is straightforward enough that AI coding assistants can generate the integration code for you from the documentation alone.

## How do I handle missing data or optional fields in generated images?

RenderStack has built-in fallback chains. For each dynamic layer, you define an ordered strategy: try API-provided data first, fall back to initials, then a default value, or hide the element entirely. Auto-layout containers automatically reflow remaining elements when something hides. This means zero client-side logic for handling edge cases — the template handles it all.

## Can I generate images with variable numbers of items, like speaker cards or product grids?

Yes — repeater elements let you render 1 to N items from a single template. Define a repeater container in the editor, design one item layout, and send an array of data via the API. RenderStack clones the item for each entry, positions them according to your layout rules, and handles overflow automatically. One template covers any count.

## Does RenderStack support custom fonts in generated images and PDFs?

Yes. 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 — WOFF and WOFF2 fonts are automatically converted for server-side rendering, so no manual conversion is needed. Your generated images and PDFs will use your exact brand typography with full control over weight, size, spacing, and alignment.

## How do I add QR codes to dynamically generated images?

Add a QR code element in the template editor and mark it as dynamic. When you call the API, pass the URL or data string as an override, and RenderStack generates and embeds the QR code at render time. You can customize the size, position, and error correction level. If the QR data is invalid, the render continues with a warning instead of failing.

## Is RenderStack suitable for e-commerce product image generation?

Yes. Design a product card template with placeholders for product name, price, image, badge, and description. Mark each as dynamic, then call the API with product data from your catalog to generate consistent, on-brand product images at scale. Auto-layout containers handle variable text lengths, and fallback chains gracefully handle missing product photos.

## How does RenderStack compare to using Puppeteer or headless Chrome for image generation?

Puppeteer and headless Chrome require you to maintain browser infrastructure, handle memory leaks, manage timeouts, and debug CSS rendering inconsistencies. RenderStack eliminates all of that — you design visually in a dedicated editor, and the server-side rendering engine produces deterministic output every time without a browser. It's faster, more reliable, and requires zero DevOps overhead.

## Can I upload a design mockup and convert it to an API-ready template?

Yes. RenderStack's AI Template Creation feature lets you upload a PNG, JPG, WebP, or PDF file. AI vision analyzes the layout, detects text blocks, image regions, shapes, and spatial relationships, then generates an editable template with properly positioned elements. You refine it in the visual editor and it's immediately ready for API rendering.

## What output formats does RenderStack support?

RenderStack renders to PNG (best for graphics with transparency), JPEG (best for photos, configurable quality 1-100), and PDF (including multi-page documents with up to 50 pages per render). You can set default output preferences globally or override the format per render request.

## How does team collaboration work in RenderStack?

RenderStack supports multi-tenancy with role-based access control. Create an organization, invite team members as owners, admins, users, or viewers — each role has specific permissions for templates, API keys, assets, and settings. All data is isolated per organization, and the activity log tracks every action by every member for full auditability.

## Can I auto-upload rendered images to my own AWS S3 bucket?

Yes. Configure your AWS S3 credentials once in settings (encrypted with AES-256-GCM at rest), and toggle S3 upload per render request. Rendered images are automatically uploaded to your bucket after generation. The upload is non-blocking — if S3 fails, the render still succeeds and you still get your image.

## Does RenderStack support outbound webhooks for event notifications?

Yes. RenderStack provides outbound webhooks that send real-time HTTPS notifications to your systems when important events occur — renders completing or failing, templates being created or updated, team membership changes, usage limits approaching, and subscription events. Each webhook payload is signed with HMAC-SHA256 so you can verify authenticity. Failed deliveries are automatically retried with exponential backoff, and you can view delivery history, test endpoints, and rotate signing secrets from the Webhooks page.

## How does RenderStack handle email notifications?

RenderStack sends email notifications for key events like payment failures, trial expiry warnings, usage limit alerts, account status changes, and team activity. You control which notifications you receive from your profile preferences, and every email includes a one-click unsubscribe link. Organization owners automatically receive critical billing and account alerts, while all users get a one-time welcome email upon signup.

## Can I convert a template element from one type to another, like text to image?

Yes. In the template editor, select any element and use the **Type** dropdown in the Properties panel to convert it to a different type — for example, switch a text frame to an image frame, or a rectangle to an ellipse. Compatible properties like position, size, fill color, stroke, and corner radius carry over automatically. This is especially useful when refining templates created by AI image analysis, where a detected element may need to be reclassified (e.g., a text region that should actually be an image placeholder).

## How does image caching work, and how can I improve rendering performance?

RenderStack automatically caches images rendered via the GET endpoint (`/api/v1/render`). When the same URL with the same parameters is requested again, the cached version is served instantly — no re-rendering required. Response headers include `X-Cache: HIT` or `X-Cache: MISS` so you can verify caching behavior. Cache TTL varies by plan, and Enterprise customers can customize their cache settings directly from the Settings page. You can purge cached images via the API — individually by cache key, by template, or for your entire organization. When you edit a template, its cached images are automatically invalidated. For additional performance, place a CDN like Cloudflare or CloudFront in front of the GET render endpoint to cache responses at the edge, reducing latency for global audiences. View your cache usage and hit rates on the Billing page.

## Is there a free tier or trial available?

Yes. RenderStack offers a free trial so you can design templates, test the API, and generate renders without a credit card. When you're ready to scale, choose from flexible paid plans with usage-based pricing and optional overage allowances. Visit the Pricing page to see current plan details.