A serverless JavaScript execution platform for running custom logic, generating PDFs and screenshots, and building headless forms inside Make, n8n, or a plain HTTP API.
One-time payment on AppSumo. Backed by AppSumo's 60-day money-back guarantee.
| Website | customjs.space |
| Category | Development |
| Alternative to | PDF-API.io, The PDF Maker, and other headless PDF or automation APIs |
| Best for | Developers and no-code automation builders who need JavaScript logic, PDFs, or screenshots inside Make, n8n, or a custom app |
| Deal price | $49 one-time (regularly $360) |
| Refund window | 60 days, per AppSumo's standard policy |
CustomJS was built by founder Henrik Lippke around a specific frustration: getting a form submission turned into a PDF, or a webpage turned into a screenshot, usually means stitching together four separate tools and a webhook. CustomJS collapses that into one serverless JavaScript execution environment that can be called from Make.com, n8n, or a plain HTTP request, so dynamic processing like HTML-to-PDF conversion, screenshots, and web scraping runs through a single API instead of a chain of services.
The platform supports two execution modes. Inline execution sends JavaScript directly in the request body, useful for quick tests or one-off runs, while stored execution saves a function on the CustomJS platform and references it by ID, which is the pattern most people use for production workflows since it supports versioning and sharing logic across automations. Beyond raw code execution, CustomJS packages several ready-made use cases: an HTML-to-PDF API for pixel-perfect document generation, a screenshot API for capturing web pages, HTML hosting that turns pasted HTML into a live URL, headless forms with a drag-and-drop editor that route submissions to Make, n8n, Airtable, Notion, or any HTTP endpoint, and a mail hook feature for forwarding incoming email to a webhook.
For teams already building in Make.com or n8n, CustomJS ships official modules and nodes so PDF generation, screenshots, and custom logic can be dropped into an existing automation without writing boilerplate integration code. For developers working outside those platforms, the same functions are callable directly over HTTP, which makes CustomJS reasonably flexible whether the rest of a stack is no-code or fully custom.
CustomJS's AppSumo lifetime deal maps to a Pro tier and two higher Ultra tiers, scaling monthly document and execution limits as you move up. For context, CustomJS's own free plan alone includes 600 free documents a month, which gives a useful baseline for how much usage the paid lifetime tiers are built to handle.
| Tier | Price | Notable limits |
|---|---|---|
| Pro (Tier 1) | $49 | Core JavaScript execution, PDF and screenshot generation, headless forms |
| Ultra (Tier 2) | Check current AppSumo listing | Higher monthly execution and document limits |
| Ultra (Tier 3) | Check current AppSumo listing | Highest lifetime execution and document limits |
Exact monthly document and execution caps per tier can shift during an active AppSumo campaign, so confirm current limits on the deal page before choosing a tier.
CustomJS fits developers and technical no-code builders who already work inside Make.com or n8n and need a way to run custom JavaScript, generate PDFs or screenshots, or stand up a headless form backend without adding three separate vendor subscriptions to the stack. Agencies building client automations, and SaaS teams that need programmatic invoice or report generation, are typical use cases.
If your only need is a drag-and-drop PDF template builder with no code involved, a tool built specifically around that single use case may get you there faster than a general-purpose JavaScript execution platform like CustomJS.
Basic use, especially templates and pre-built use cases like the HTML-to-PDF API, requires little to no code, but getting the most out of stored functions and custom logic benefits from JavaScript familiarity.
Yes, CustomJS ships official modules for Make.com and nodes for n8n, so PDF generation, screenshots, and custom logic can be added directly to existing automations.
Yes, the HTML-to-PDF API converts HTML or templates enriched with dynamic data into pixel-perfect PDF documents through dedicated API endpoints.
Inline execution sends code directly in the request body for quick, one-off runs, while stored execution saves the function on CustomJS and references it by ID, which supports versioning and reuse in production.
Yes, CustomJS includes a headless form builder with a drag-and-drop editor that routes submissions to Make, n8n, Airtable, Notion, or any HTTP endpoint.
Get the CustomJS lifetime deal on AppSumo to run JavaScript, generate PDFs and screenshots, and build headless forms for a one-time payment, backed by AppSumo's 60-day money-back guarantee.
Get Lifetime Access →