Overview
Firma.dev and Schema Source by Tabstack are two developer tools that serve completely different purposes. Firma.dev is a low-cost, white-label e-signature API designed for SaaS platforms that need to embed document signing. Schema Source by Tabstack is a free tool that extracts JSON schemas from any URL, outputting them as JSON Schema, Zod objects, or Pydantic models. This comparison highlights their features, pricing, and ideal use cases.
Feature Comparison
| Feature | Firma.dev | Schema Source by Tabstack |
|---|---|---|
| Primary Function | E-signature API for embedding document signing into SaaS apps | JSON Schema extraction tool for any URL |
| Target Audience | Developers, SaaS teams, startups needing white-label e-signatures | Developers needing structured data schemas from web pages |
| Integration Method | REST API, embeddable iFrame, pre-built UI components | Paste URL → get schema; also accessible via API with JSON content negotiation |
| Output Formats | Signed documents, audit trails, completion certificates | JSON Schema, Zod object, Pydantic model |
| White-Labeling | Fully white-label with custom branding and UX | Not applicable |
| Pricing Model | Pay-as-you-go: €0.029 per envelope, no monthly fees | Free |
| Compliance | SOC 2, ISO 27001, eIDAS, GDPR, ESIGN, UETA | Not specified |
| Real-time Features | Webhooks, event streams, real-time status updates | Cached schema results, no real-time streaming |
| Team Management | Unlimited teams with data isolation and permissions | Not applicable |
| Developer Tools | Swagger/OpenAPI docs, sample apps, webhooks | Simple paste-and-copy workflow, API for cached schemas |
Pricing
Firma.dev: Pay-as-you-go at €0.029 per envelope (about 3¢). No monthly fees, no minimums, no contracts. Free sandbox with unlimited test usage.
Schema Source by Tabstack: Completely free. No pricing tiers or paid plans.
Pros and Cons
Firma.dev
Pros:
- Extremely low cost compared to competitors like DocuSign
- Developer-first with clean REST API and quick integration
- Fully white-label and resell-ready for SaaS platforms
- Strong compliance certifications (SOC 2, ISO 27001, eIDAS, GDPR)
- Free sandbox with unlimited test usage
Cons:
- Only supports envelope-based pricing, may not suit very high-volume users
- Limited to e-signature use case only
Schema Source by Tabstack
Pros:
- Completely free to use
- Instant schema generation from any URL
- Multiple output formats (JSON Schema, Zod, Pydantic)
- Cached results for consistent and fast retrieval
- Backed by Mozilla (via Tabstack)
Cons:
- Niche use case – only extracts schemas, not a full e-signature solution
- No white-labeling or team management features
- No compliance certifications mentioned
Verdict
Choose Firma.dev if you need a cost-effective, developer-friendly e-signature API with white-labeling and strong compliance for your SaaS product. Choose Schema Source by Tabstack if you need a free, instant tool to extract JSON schemas from web pages for data extraction or validation. They serve entirely different purposes, so the right choice depends on whether your project requires document signing or structured data schema generation.
Firma.dev
Schema Source by Tabstack