canonical: https://jentic.com/apis/diffchecker.com/diffchecker

# Diffchecker API

The Diffchecker API compares text, documents, images, and spreadsheets and returns the differences between them. It diffs plain text, produces document redlines with Microsoft Word tracked changes, compares PDFs as plain or rich text, and highlights changes between two images or two Excel spreadsheets. A free tier is keyed to an email query parameter and paid plans use an API key.

## For AI agents

Compare text, PDFs, Word documents, images, and Excel spreadsheets through Diffchecker and get the differences. Produce document redlines with Word tracked changes from two versions.

## Scope

Does not handle document storage, e-signatures, or version-control hosting. Use for comparing text, documents, images, and spreadsheets only.

## Capabilities

- Compare two blocks of text and return the differences
- Produce a redline of two documents with Word tracked changes
- Compare PDFs as plain text or as rich text
- Compare two images and highlight what changed
- Compare two Excel spreadsheets cell by cell
- Verify API-key or email access with the auth-test endpoint

## Use cases

### Document Change Review

An AI agent reviews what changed between two versions of a contract or report. It sends both documents to the redline operation and returns a Word file with tracked changes a human can accept or reject. The agent discovers the redline operation through Jentic by intent, so it produces the comparison without hardcoding endpoint paths.

Example prompt: Send two versions of a document to the redline operation and return the tracked-changes result

### Automated Text Diffing

A pipeline needs to detect changes between two text snapshots, such as config files or copy drafts. The agent posts both to the text comparison operation and acts on the diff it returns. Because the text endpoint takes the two inputs directly, the agent diffs them in a single call.

Example prompt: Compare two text snapshots and return the added and removed lines

### Spreadsheet and Image Comparison

A QA agent compares two exports to catch regressions. It compares two Excel spreadsheets cell by cell and diffs two rendered images to flag visual changes. Diffchecker handles each format on its own endpoint, so the agent picks the comparison that matches the file type.

Example prompt: Compare two Excel spreadsheets and two images, and report the cells and regions that differ

## Key endpoints

| Method | Path | Description |
| --- | --- | --- |
| POST | `/text` | Compare two blocks of text |
| POST | `/document/redline` | Produce a document redline with tracked changes |
| POST | `/document/plaintext` | Compare documents as plain text |
| POST | `/document/richtext` | Compare documents as rich text |
| POST | `/image` | Compare two images |
| POST | `/excel` | Compare two Excel spreadsheets |
| GET | `/auth-test` | Test authentication |

## Key resources

- **Text comparison** — Compare two blocks of text
- **Document comparison** — Redline documents and compare PDFs as plain or rich text
- **Image comparison** — Compare two images and highlight changes
- **Spreadsheet comparison** — Compare two Excel spreadsheets
- **Auth test** — Verify API-key or email access

## AI readiness

This API is usable in Jentic One now. Its AI-readiness score against Jentic's framework shows where it stands today and where improvements would make it even easier for agents to use.

- **Score:** 59 / 100
- **Maturity:** Foundational
- **Dimensions:**
  - Foundational Compliance: 81 / 100
  - Developer Experience & Jentic Compatibility: 72 / 100
  - AI-Readiness & Agent Experience: 44 / 100
  - Agent Usability: 94 / 100
  - Security: 33 / 100
  - AI Discoverability: 89 / 100
- **View full report:** https://jentic.com/apis/diffchecker.com/diffchecker/scorecard
- **How the score is calculated:** https://docs.jentic.com/reference/api-readiness-framework/overview/
- **More about the dimensions:** https://docs.jentic.com/reference/api-readiness-framework/specification/#dimensional-model-overview

### Score it yourself

Every API in the directory is allowlisted, so you can re-score it with no key required.

- **Score your own API:** https://jentic.com/scorecard.md
- **Scoring CLI agent skill:** https://github.com/jentic/jentic-api-scorecard/blob/main/skills/jentic-api-scorecard/SKILL.md

```sh
npx @jentic/api-scorecard-cli score <openapi-url>
```

## Why Jentic

- **Setup:** Wiring Diffchecker by hand means choosing between its free email-query access and a paid X-Api-Key header, then posting each comparison type to its own endpoint. Through Jentic you install once, import Diffchecker from the API Directory, store the key once, and your agent calls it.
- **Permission scoping:** You choose which Diffchecker operations your agent may call, so you can allow text and image comparison while leaving document redlines or spreadsheet diffs out unless you add them. The comparison endpoints are independent, so a rule can expose just the ones your agent needs.
- **Credential handling:** Your Diffchecker key is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.
- **Discovery method:** Agents search Jentic by intent such as compare two documents or diff two images, and Jentic returns the matching Diffchecker operation with its input schema so the agent calls the right endpoint without reading the reference docs.

## Related APIs

- **PDF.co** — PDF.co offers broad PDF processing including some comparison; Diffchecker specializes in diffing text, documents, images, and spreadsheets.
- **iLovePDF** — iLovePDF converts and edits PDFs; Diffchecker compares the resulting documents.
- **CraftMyPDF** — CraftMyPDF generates PDFs from templates; Diffchecker checks what changed between two generated outputs.

## FAQ

### What authentication does the Diffchecker API use?

The Diffchecker API supports two methods per its OpenAPI spec: an API key sent in the X-Api-Key header for paid plans, and a free tier keyed to an email address passed as a query parameter. Through Jentic the key is stored encrypted by your own Jentic One instance and injected at call time, so it never lands in the agent's prompt or logs.

### Can I compare documents with the Diffchecker API?

Yes. The redline operation compares two documents and returns Microsoft Word tracked changes, and separate operations compare PDFs as plain text or rich text. You can also compare text, images, and Excel spreadsheets on their own endpoints.

### What are the rate limits for the Diffchecker API?

The spec documents a free-tier allowance of 50 diffs per month counted against both your email and IP address. Paid API-key plans raise the allowance, and the current paid limits are listed on Diffchecker's Public API page.

### Can I limit what my agent is allowed to do with the Diffchecker API?

Yes. Write a rule that allows only the comparison types your agent needs, such as text and image comparison, while document redlines and spreadsheet diffs stay out unless you add them. Every call the agent makes is logged.

### How do I compare two documents with the Diffchecker API through Jentic?

Search Jentic for an intent like redline two documents, store your Diffchecker key once, and your agent sends both versions to the redline operation and reads back the tracked-changes result. To run it on your own infrastructure, install Jentic One from its GitHub repo.

### Is there a Diffchecker MCP server?

You don't need an MCP server to give your agent the Diffchecker API. Jentic connects it directly from the API Directory: import it, store your key once, and your agent calls the comparison operations it needs on demand.