Anvil PDF Generation API

Overview

Anvil PDF Generation API turns HTML, CSS, Markdown and JSON data into PDFs for applications and paperwork workflows. It is best suited to developers who need programmable output alongside form-filling and workflow options. Its flexible document controls are balanced by metered API charges and a TTF-only rule for custom fonts.

Key features

HTML-to-PDF supports full CSS, page dimensions and margins, headers, footers, page numbers, and fillable fields. Those controls suit branded documents and layouts that vary in length; teams with existing OTF or WOFF fonts will need to convert or choose another route, since Anvil accepts custom fonts only in TTF format.

Markdown provides a more structured input path, including tables and images. It uses a default theme, but callers can provide CSS when that presentation needs adjustment. Dynamic, variable-length documents and reusable forms make the API useful for recurring paperwork assembled from changing data.

SDKs are available for C#/.NET, JavaScript, Python, and TypeScript; Go, Java, PHP, and Ruby are marked as coming soon. Zapier can automate paperwork, including filling a PDF or starting or pre-filling an Anvil Workflow. Anvil lists SOC 2 and HIPAA compliance. It says signed documents are encrypted with a 2048 RSA private key held in a secure Hardware Security Module that its developers cannot access.

Pricing

The Free plan costs nothing and supports two users, but is UI-only. API key access requires adding a credit card or upgrading. Enabling metered usage with a valid card brings 2,500 starter credits; test mode is free and unlimited on every plan, though test documents are watermarked and use demo signatures. That makes Free useful for trying the interface and test flow, not a no-cost production API.

API PDF filling or generation costs $0.10, paid once on a pay-as-you-go basis. Paid API use requires a valid credit card, and bulk quantities start at 25,000+. The per-use model suits variable demand, but teams should account for usage rather than assuming the monthly plan price covers API calls.

AI Pack costs $99 a month, billed $99/mo, for five users. It adds programmatic Document AI, a 50-page limit per AI-tagged PDF and a higher rate limit of 40 requests per second. It fits technical teams working with high PDF volumes that need those AI features; it is not the cheapest path if the need is only PDF generation.

Product Pack costs $425 a month, billed $425/mo, for five users. It includes AI Pack features plus white labeling and advanced signing features, making it a better fit where branding and signing capabilities justify the higher monthly commitment. Enterprise has custom pricing and unlimited users, with SSO, HIPAA, DPA, priority support and customer success for organizations needing those provisions.

Platforms

Anvil is available through API and web, with cloud deployment and email support. The combination serves teams building documents into software as well as users working in a browser; those requiring self-hosted deployment should look elsewhere.

Who it's for

Anvil is a strong fit for developers and technical teams generating variable documents from HTML, CSS, Markdown or data, especially when fillable forms and Zapier-driven workflows belong in the same process. It is less suitable for teams that need a self-hosted service, depend on OTF or WOFF fonts, or want predictable API costs without tracking usage.

Pros and cons

• Pros: Multiple input formats and detailed page controls support branded, dynamic output.
• Pros: Unlimited free test mode lets teams evaluate requests without quota use or charges.
• Pros: SDKs, Zapier and fillable forms give developers several ways to connect PDF work to applications and workflows.
• Cons: The free plan is UI-only; API access requires a card or upgrade, and production API use is metered.
• Cons: Custom fonts are limited to TTF, ruling out direct use of OTF and WOFF.
• Cons: The five-user caps on AI Pack and Product Pack may not suit larger teams unless they move to Enterprise.

Alternatives

For document-template management, see Document Template Management Software; for a broader set of PDF tools, see PDF Creation Software.

Docxtemplater is worth considering if its open-source option and wider platform coverage, including self-hosting, better match your setup. Carbone is another freemium option with a free trial and self-hosted platform support. Docassemble is a free alternative for teams prepared to self-host; hosting typically costs $10–$40 per month or more depending on performance, availability and support needs.

Documentero may suit teams that want a defined free allowance of 50 documents and three templates, with cloud API service. Legito is an alternative for document lifecycle management, customizable workflows and approvals, and electronic signatures. PDFMonkey offers a free tier of 20 documents per month, but with one-day retention and restrictions on external images, fonts, CSS and JavaScript.

Marq is a web-based alternative with a free plan limited to one user, 25 MB of cloud storage and three projects. Fluent by Apryse is another option for teams willing to consider custom-priced packages starting at $1,500 per contact.

Verdict

Choose Anvil if you need an API for dynamic PDF generation and want form filling, workflow automation and document controls in the same service. Its strongest advantage is the range of input formats and layout options, supported by free test mode. Look elsewhere if your font assets are OTF or WOFF, you need self-hosting, or per-use API billing is a poor fit.