Can AttachKit chat across many PDFs like PDF.ai?

Not the same way. PDF.ai keeps a persistent, searchable library and answers questions across many uploaded documents at once — that's its core strength, and it's genuinely good at it. AttachKit's agent can summarize and answer questions about the document you're working on (using 10 AI actions/mo on the free tier), but it isn't a multi-document research library. If you mainly want to interrogate a big corpus, PDF.ai is the better reader; if you want to act on a file privately, AttachKit is the tool.

Does PDF.ai store my document?

By default, yes — PDF.ai's chat product uploads your file and keeps it in your document library so you can return to it, with a "private" setting to opt out of storage. AttachKit never uploads the file at all: everything runs in your browser, which you can confirm in DevTools → Network, and only extracted text is sent to the model. For the AI features (auto-fill, PII detection, clause review, single-doc Q&A), Local AI mode keeps even that on your own machine; the agent's planning step is the cloud-only exception.

Can PDF.ai fill or redact a form for me?

Its AI chat can't — it reads and answers questions. PDF.ai does host separate one-off tools (merge, split, eSign, compress, convert), but they're standalone, not part of the AI. AttachKit's agent takes a plain-language instruction, proposes the exact edits — fill, replace text, redact, reorder — and applies them only after you approve, all in your browser.

Should I use PDF.ai or AttachKit?

For research — summarizing and querying long or many documents with citations — PDF.ai is built for that and does it well. For acting on a PDF — filling forms, redacting PII, signing, reorganizing pages — without your file ever being uploaded or stored, AttachKit is the one that does the work. Many people will want both: PDF.ai to understand a document, AttachKit to change it privately.

Alternative · PDF.ai

AttachKit vs. PDF.ai — chat that reads your file vs. an agent that edits it, without the upload

PDF.ai: A popular "chat with any PDF" tool — upload a document and ask it questions, get summaries and cited answers, with a developer API for parsing and extraction.

PDF.ai is one of the best-known "chat with your PDF" tools: upload a document and it answers questions, summarizes, cites the passages, and can even query across several PDFs at once — a genuinely useful research chat, backed by GPT models and a developer API. But that convenience has an architecture: the chat product uploads your file to PDF.ai's servers and, by default, STORES it in your document library (you can mark a document "private" to opt out of storage). And it only ever talks ABOUT the file — the AI chat itself can't fill a field, redact a line, or reorder a page (PDF.ai does host a separate set of one-off PDF utilities, but that's not the AI experience). AttachKit is the opposite shape: its Private PDF Agent acts ON the document — you describe the change in plain language, it proposes a reviewable plan (rotate, delete, reorder, extract, replace text, stamp, watermark, Bates-number), and nothing is applied until you approve. The file never leaves your browser — provable in DevTools → Network — and the AI only ever sees extracted text, never the document itself.

Why pick AttachKit for these cases

The AI acts on your PDF — an agent that fills, redacts, signs, and reorganizes — instead of only chatting about it.
Your file never leaves the browser; PDF.ai uploads it and, by default, stores it. Only extracted text ever reaches the model.
Every agent edit is a reviewable plan you approve before anything is applied — no surprise changes.
Optional Local AI mode (your own Ollama) runs the AI features on your machine so no third-party model sees even the text — the agent's planning step stays cloud-only.
One tool for reading AND doing — fill, sign, redact, convert, OCR — not a read-only chat window plus a separate utilities page.

Side-by-side

A marks the side with the genuine advantage on that row — honestly, including the few where PDF.ai wins.

Where your file goes

PDF.aiUploaded to PDF.ai's servers to chat with, and STORED by default in your document library; you can set a document "private" to opt out of storage. AI processing runs on an external model provider.

AttachKitNowhere — the PDF stays in your browser. Open your Network tab and watch: the file is never uploaded. Only extracted text is sent to the AI, never the document.

What the AI does

PDF.aiAnswers questions ABOUT the document — chat, Q&A, summaries, cited answers, and querying across multiple PDFs. It reads; the chat product does not edit the file.

AttachKitThe agent ACTS on the document: describe a change and it proposes edits (replace text, delete/reorder/extract pages, stamp, watermark, number) you approve before anything mutates — and it answers questions about the open doc too, with page cites. Fill, redaction, and signing are AttachKit tools alongside it.

Editing the PDF

PDF.aiThe AI chat can't fill, redact, sign, or reorganize. PDF.ai does host a separate suite of one-off PDF tools (merge, split, eSign, compress, convert), but they're standalone utilities, not part of the chat.

AttachKitThe core purpose — fill, sign (PAdES-aligned, verifiable), redact with PII detection, reorder/extract pages, convert, OCR — all in your browser, driven by the agent or by hand.

Propose-then-apply safety

PDF.aiN/A for the chat — it returns text answers; there's nothing to apply.

AttachKitEvery agent request becomes a reviewable plan of operations. You see exactly what will change and approve it before a single byte is mutated.

Multi-document research chat

PDF.aiA real strength — a persistent, searchable document library plus cross-document Q&A with citations is exactly what PDF.ai is built for, with GPT-4-class models and "Capture & Ask" screenshot Q&A.

AttachKitAttachKit's agent answers questions about the document you're working on, but it isn't a persistent multi-document research library. For deep Q&A across many files at once, a dedicated reader like PDF.ai is the better tool.

Developer API & integrations

PDF.aiA hosted parse/extract/ask API, AI Agents, an embeddable chatbot widget, team seats, and a Chrome extension — real reach for building document features into other software.

AttachKitA finished app, not a platform. There's a Max-tier API and an embeddable verifier, but it isn't a hosted document-chat API you build products on.

Price

PDF.aiA free tier plus paid subscriptions and a separate credit-based API — pricing and tiers change and are best confirmed on pdf.ai's live pricing page.

AttachKitFree: unlimited fill/redact/OCR + 10 AI actions/mo (edited-PDF exports capped on Free; unlimited on paid). Pro $12/mo (or $120/yr — $10/mo) with 200 AI actions/mo; Max $19/mo adds 500. Prices change — check the pricing page.

Local-only AI option

PDF.aiCloud-based — your uploaded document is processed on external servers to generate answers.

AttachKitOptional Local AI mode runs the AI features (auto-fill, PII detection, clause review, single-doc Q&A) on your own Ollama, so no third-party AI sees even the extracted text. The agent's planning step is cloud-only and isn't covered by Local AI mode.

	PDF.ai	AttachKit
Where your file goes	Uploaded to PDF.ai's servers to chat with, and STORED by default in your document library; you can set a document "private" to opt out of storage. AI processing runs on an external model provider.	Nowhere — the PDF stays in your browser. Open your Network tab and watch: the file is never uploaded. Only extracted text is sent to the AI, never the document.
What the AI does	Answers questions ABOUT the document — chat, Q&A, summaries, cited answers, and querying across multiple PDFs. It reads; the chat product does not edit the file.	The agent ACTS on the document: describe a change and it proposes edits (replace text, delete/reorder/extract pages, stamp, watermark, number) you approve before anything mutates — and it answers questions about the open doc too, with page cites. Fill, redaction, and signing are AttachKit tools alongside it.
Editing the PDF	The AI chat can't fill, redact, sign, or reorganize. PDF.ai does host a separate suite of one-off PDF tools (merge, split, eSign, compress, convert), but they're standalone utilities, not part of the chat.	The core purpose — fill, sign (PAdES-aligned, verifiable), redact with PII detection, reorder/extract pages, convert, OCR — all in your browser, driven by the agent or by hand.
Propose-then-apply safety	N/A for the chat — it returns text answers; there's nothing to apply.	Every agent request becomes a reviewable plan of operations. You see exactly what will change and approve it before a single byte is mutated.
Multi-document research chat	A real strength — a persistent, searchable document library plus cross-document Q&A with citations is exactly what PDF.ai is built for, with GPT-4-class models and "Capture & Ask" screenshot Q&A.	AttachKit's agent answers questions about the document you're working on, but it isn't a persistent multi-document research library. For deep Q&A across many files at once, a dedicated reader like PDF.ai is the better tool.
Developer API & integrations	A hosted parse/extract/ask API, AI Agents, an embeddable chatbot widget, team seats, and a Chrome extension — real reach for building document features into other software.	A finished app, not a platform. There's a Max-tier API and an embeddable verifier, but it isn't a hosted document-chat API you build products on.
Price	A free tier plus paid subscriptions and a separate credit-based API — pricing and tiers change and are best confirmed on pdf.ai's live pricing page.	Free: unlimited fill/redact/OCR + 10 AI actions/mo (edited-PDF exports capped on Free; unlimited on paid). Pro $12/mo (or $120/yr — $10/mo) with 200 AI actions/mo; Max $19/mo adds 500. Prices change — check the pricing page.
Local-only AI option	Cloud-based — your uploaded document is processed on external servers to generate answers.	Optional Local AI mode runs the AI features (auto-fill, PII detection, clause review, single-doc Q&A) on your own Ollama, so no third-party AI sees even the extracted text. The agent's planning step is cloud-only and isn't covered by Local AI mode.

Switching questions, answered

Can AttachKit chat across many PDFs like PDF.ai?: Not the same way. PDF.ai keeps a persistent, searchable library and answers questions across many uploaded documents at once — that's its core strength, and it's genuinely good at it. AttachKit's agent can summarize and answer questions about the document you're working on (using 10 AI actions/mo on the free tier), but it isn't a multi-document research library. If you mainly want to interrogate a big corpus, PDF.ai is the better reader; if you want to act on a file privately, AttachKit is the tool.
Does PDF.ai store my document?: By default, yes — PDF.ai's chat product uploads your file and keeps it in your document library so you can return to it, with a "private" setting to opt out of storage. AttachKit never uploads the file at all: everything runs in your browser, which you can confirm in DevTools → Network, and only extracted text is sent to the model. For the AI features (auto-fill, PII detection, clause review, single-doc Q&A), Local AI mode keeps even that on your own machine; the agent's planning step is the cloud-only exception.
Can PDF.ai fill or redact a form for me?: Its AI chat can't — it reads and answers questions. PDF.ai does host separate one-off tools (merge, split, eSign, compress, convert), but they're standalone, not part of the AI. AttachKit's agent takes a plain-language instruction, proposes the exact edits — fill, replace text, redact, reorder — and applies them only after you approve, all in your browser.
Should I use PDF.ai or AttachKit?: For research — summarizing and querying long or many documents with citations — PDF.ai is built for that and does it well. For acting on a PDF — filling forms, redacting PII, signing, reorganizing pages — without your file ever being uploaded or stored, AttachKit is the one that does the work. Many people will want both: PDF.ai to understand a document, AttachKit to change it privately.

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