Help & Support

LineDiff is an AI‑assisted diff workspace for professionals working with high‑stakes documents such as contracts, policies, financial reports and specifications. You can compare long texts and multi‑format documents, add line‑level comments, work securely across devices and, when needed, use AI‑powered semantic insights to understand not just what changed, but why it matters.

Using LineDiff is simple: Upload or paste the two texts or files you want to compare, or import from formats like PDF, Word, Excel or Google Docs. LineDiff automatically highlights differences in side‑by‑side or line‑by‑line view. You can add comments, apply original/modified text with one click, export reports, and optionally run AI‑powered semantic analysis when you need deeper insight.

LineDiff analyzes the uploaded text or files line by line and character by character, highlighting differences so you can see exactly what has changed.

You can export in PDF, HTML, Excel and JSON formats, so you can create client‑ready reports, internal tracking sheets or machine‑readable outputs for automation.

Yes! You can attach comments to any line, with author information and timestamps, making it easy to track decisions, rationale and questions for future reference.

AI-powered semantic diff is optional and credit-based. Pro users get 50 welcome credits (one-time), Team users get 150/user. Credits never expire. Cost depends on model (GPT-5 Nano=1, GPT-5 Mini=2, GPT-5/5.1=4 base credits) multiplied by text size (S=1x, M=2x, L=3x, XL=5x). Additional credit packs: Starter (25/$3), Plus (100/$10), Pro (500/$40). AI requires login, consent, and sufficient credits.

LineDiff supports TXT, MD, JSON, XML, HTML, YAML, CSS, JS and many programming language files.

Yes! LineDiff supports JSON, HTML, and YAML, allowing you to easily identify changes in code files.

Yes, you can upload PDF, Word, and Excel documents to compare their content. LineDiff will analyze the differences and highlight them.

Side-by-side mode lets you compare two texts or files by placing them side by side. Line-by-line mode lets you examine two texts or files one above the other.

Yes! LineDiff offers the following filtering options: Ignore spaces, Ignore case differences, Trim leading & trailing spaces, Ignore accents.

Yes! LineDiff saves your comparison history, allowing you to access previous analyses from the "History" tab anytime.

LineDiff offers a Free plan with unlimited classic diff comparisons, 10 exports/month (excluding PDF), 3 Google Docs imports/month, and 50 history items. For advanced features like PDF export, sharing, and AI credits, we offer Pro ($14.25/mo launch | $19/mo regular) and Team plans. AI credits included in paid plans never expire, and additional credit packs can be purchased anytime.

Free: Unlimited classic diff, 10 exports/month (no PDF), 3 Google Docs imports, 50 history items, local comments. Pro ($14.25/mo launch): 50 PDF exports, 200 other exports, 30 Google Docs imports, 1,000 history, 50 shares, 50 welcome AI credits (never expire), cloud sync. Team ($44.25/user/mo launch): 200 PDF exports/user, 500 other exports/user, 100 Google Docs/user, 5,000 history/user, 200 shares/user, 150 AI credits/user, workspace management, SLA support.

Export limits reset monthly. Free plan: 0 PDF exports, 10 other exports (HTML, Excel, JSON, Text). Pro plan: 50 PDF exports, 200 other exports per month. Team plan: 200 PDF exports/user, 500 other exports/user per month. Enterprise: Unlimited exports. Note: PDF export requires a Pro or higher plan due to server-side processing costs.

Yes. LineDiff prioritizes your data security. For logged-in users, data syncs to the cloud (Firestore) with optional encryption—you choose encrypted (client-side encryption, zero-knowledge) or unencrypted storage per comparison. For guests (not logged in), data stays only in your browser (IndexedDB) and never leaves your device. We only store the minimum metadata needed for history, sharing, and AI usage tracking.

Encrypted comparisons use a document key (access key) stored only in your browser. To access on another device: 1) Open the comparison where it works, 2) Copy the access key from the Share modal or History list key icon, 3) On the new device, open the comparison and paste the key to unlock. Important: If you lose access everywhere and never saved the key, encrypted content cannot be recovered - this is by design for maximum security.

Yes. LineDiff is built for legal workflows. Upload two versions of any contract (Word, PDF, or text) and LineDiff highlights every changed word, clause, and sentence instantly. The AI Legal domain analysis identifies critical clause modifications — added obligations, removed protections, changed liability terms, and risk-flagged language — so attorneys can focus their review on the most significant changes. Zero-knowledge client-side encryption protects attorney-client privileged content: documents are encrypted in your browser before any data leaves your device, and LineDiff's server never sees unencrypted content.

LineDiff supports Excel (.xlsx), CSV, and PDF formats commonly used in financial reporting. Compare quarterly reports, budget spreadsheets, or regulatory filings version by version with cell-level precision for Excel and row-level precision for CSV. The AI Finance domain analysis flags material differences — significant numerical shifts, added or removed line items, changed subtotals, and discrepancies that warrant attention before submission. PDF export creates timestamped comparison reports suitable for audit trails and regulatory documentation.

Absolutely. LineDiff is ideal for procurement workflows. Upload two vendor proposals (Word, PDF, or Excel) side by side and instantly see every difference in scope, pricing, delivery terms, and technical specifications. For pricing matrices, Excel and CSV support enables cell-level comparison of rate cards and cost breakdowns. The AI SCM domain analysis flags commercially significant deviations from RFP requirements, non-standard payment terms, and scope exclusions. Role-based sharing lets the CPO maintain control while category managers annotate and stakeholders review.

LineDiff offers 8 specialized AI domains that provide context-aware semantic analysis of your diffs: Legal (clause risk, obligations, liability), Finance (material differences, audit flags), SCM/Supply Chain (commercial terms, pricing deviations), Academic (methodology, citations, conclusions), Pharma/Medical (dosage, contraindications, protocols), Tech (config impact, breaking changes), Publishing (tone, narrative, structure), and General. Each domain uses GPT-5 models trained to understand industry-specific terminology and flag changes that matter most in your professional context.

Yes. LineDiff supports BYOK (Bring Your Own Key) — you can connect your own OpenAI API key in Settings. When BYOK is enabled, AI analysis requests are routed through your own API key instead of consuming LineDiff credits. This is ideal for teams with existing OpenAI agreements, organizations that require data processing through their own API accounts for compliance reasons, or power users who want unlimited AI analysis without purchasing credit packs.