TL;DR. Pick Laper if you want a focused, AI-powered screenwriting editor with real-time collaboration — without paying for production-planning features you may never use. Pick Celtx if you genuinely need scheduling, budgeting, storyboards, and call sheets in one software and are willing to accept a slower, heavier writing experience.
Start free. Junior is free, no credit card required. Import a .fdx, test one writing session, and only upgrade if Laper's editor, AI, and collaboration actually fit your workflow. Start free on Laper · View pricing
Quick Verdict
| Use case | Recommended software |
|---|---|
| You want a fast, modern editor that disappears when you write | Laper |
| You want AI suggestions grounded in your full screenplay | Laper |
| You want real-time character-by-character co-writing | Laper |
| You need bundled pre-production planning (budgets, schedules, call sheets) | Celtx |
| You manage indie production end-to-end inside one software | Celtx |
| You write in Chinese / want first-class multilingual support | Laper |
Celtx was one of the original web-based screenwriting software and has since evolved into a broader pre-production suite. Laper is a younger product focused on the writing layer first — AI-native, CRDT-collaborative, designed to disappear when you are in flow.
Feature Comparison
| Feature | Laper | Celtx |
|---|---|---|
| Primary focus | Screenplay writing with AI, with auto-derived production views. | All-in-one pre-production suite (script + scheduling + budgeting + storyboards). |
| Real-time collaboration | CRDT-based, conflict-free, browser-native co-writing. Two writers in the same scene merge cleanly. | Cloud-shared projects and collaboration features across the Celtx workspace. |
| AI writing assistance | AI-native. Full-script context (200K+ tokens). One-click character bios, relationship graphs, storyboards, posters. | Limited AI assistance added over recent releases. Not the architectural core of the product. |
| AI visual generation | Built-in. Character portraits, scene stills, storyboards, posters, casting posters — all grounded in your screenplay. | Storyboards are manual; AI visual generation is not a primary feature. |
| Writing smoothness | Plate.js + Loro CRDT (WASM), built for responsive long-script editing without virtualization tricks. | Web-based editor inside a broader production-planning workspace. |
| Industry-standard format | Hollywood format with auto-formatting on scene heading, character, dialogue, transition. | Hollywood format. Long-standing industry compatibility. |
| Pre-production software | Auto-derived Scenes / Characters / Locations / Props from the script, plus storyboard sheets. No full scheduling/budgeting/call-sheet suite. | Bundled scheduling, budgeting, storyboards, shot lists, call sheets. The product's biggest surface area. |
| Platforms | Web (any modern browser), macOS desktop, Windows desktop. | Web; legacy desktop versions deprecated. |
| Offline editing | Desktop apps support fully offline editing; CRDT state syncs on reconnect. | Cloud-first; offline behavior is limited and not the recommended workflow. |
| Pricing | Free Junior tier; Senior $20 / mo or $192 / yr (AI included); Master $100 / mo or $960 / yr for teams. | Free/trial path plus paid Writer, Writer Pro, Team, Education, and Student options; exact price varies by billing cycle and seats. |
| Languages | English, Simplified Chinese, Spanish (more on roadmap). | English-first; limited localization. |
The honest summary: Celtx wins on bundled production planning breadth. Laper wins on writing smoothness, AI depth, real-time collaboration, and multilingual editing.
Where Laper Is Meaningfully Better
1. Writing experience and speed
Celtx is a long-running product that has accumulated layers — script editor, then scheduling, then budgeting, then storyboards, then more. The result is a broader workspace that can feel dense when your immediate job is simply to write the next scene.
Laper does the opposite. The editor is the product. The interface is opinionated about whitespace and typography; the AI panel and asset views are one click away but never in your face. If you have ever felt the software you write in was actively slowing you down, the gap is real.
2. AI grounded in your full screenplay
Most AI writing assistants see only your current paragraph. Laper's AI sees your entire screenplay (200K+ tokens of context). When you ask for a character bio, it reads every line that character has spoken across every scene. When you ask for a relationship graph, it analyzes co-appearance across the full script. When you generate a storyboard, it knows the visual continuity of the scenes before and after.
Celtx's AI features, where present, operate on smaller local context — useful, but architecturally a different category.
3. Real-time collaboration that actually merges
Celtx supports cloud-shared projects across a broader production workspace. Laper is narrower and more specific: the script editor itself is designed around character-by-character real-time merging.
Laper uses Loro CRDT, a conflict-free replication model designed for collaborative editing. Two writers in the same scene see each other's cursors and edits in real time; the merge is automatic and conflict-free, even if one writer was offline for an hour and reconnects.
4. Multilingual editing
Celtx is English-first. Laper ships with first-class English, Simplified Chinese, and Spanish — including Hollywood-equivalent Chinese screenplay formatting (人物 / 场景标题 / 动作 / 对白). For a Chinese-speaking team, this is a category Celtx does not enter.
Where Celtx Is Meaningfully Better
A comparison page that pretends the competitor has no strengths is not honest. Celtx genuinely wins on:
- Bundled pre-production planning. Scheduling, budgeting, call sheets, shot lists — Celtx ships them all in one subscription. If you actually need those software and would otherwise stitch together Movie Magic Scheduling + StudioBinder + Final Draft, Celtx is genuinely cheaper as a bundle.
- Indie production workflow. Small indie production companies that handle everything in one software have used Celtx for over a decade. The muscle memory is real and the workflow is proven.
- Maturity. Celtx has had 17 years to fix edge cases. Laper is a young product; we will hit rough edges Celtx already smoothed.
If you actually need an end-to-end production planning suite and not just a writing software, Celtx is the rational choice — and Laper is the wrong product for you.
Pricing in Plain Numbers
| Plan | Laper | Celtx |
|---|---|---|
| Free | Junior — free, no credit card, full editor + AI credits | Free/trial path with project and feature limits |
| Entry paid | Senior $20 / mo or $192 / yr (AI included) | Writer / Writer Pro pricing varies by billing cycle |
| Production tier | Master $100 / mo or $960 / yr (teams, multi-seat, higher AI quotas) | Team / education pricing varies by seats and planning software |
| AI features | Full conversational AI + visual generation, included | Limited AI assistance |
For pure writing, Laper Junior is the cheapest path (free). For bundled production planning, Celtx's higher tiers may give you more total surface area for the money — but only if you actually use scheduling, budgeting, and shot lists.
When NOT to Choose Laper
- You run an indie production company and need scheduling + budgeting + call sheets in one software. Laper is a writing-first editor; we auto-derive Scenes / Characters / Locations from your script, but we do not (yet) ship a full production planning suite. Celtx is genuinely the better software for that workflow.
- Your existing team has years of Celtx muscle memory and zero appetite for migration. Software switches have real cost. If Celtx is working, keep using it.
- You write entirely offline in environments without internet. Both software have offline limitations, but Laper's CRDT sync is most valuable when you reconnect; Celtx's cloud-first model has similar offline constraints. If you write on a remote farm with no WiFi, evaluate carefully.
Migration from Celtx
Celtx exports screenplays to PDF and Final Draft (.fdx). The recommended path into Laper today:
- Export your project from Celtx as
.fdx. - Open Laper and use the Final Draft import flow.
- Review the imported screenplay in Laper's editor.
- Check the auto-derived Scenes / Characters / Locations views.
- Keep Celtx active for projects already deep in scheduling, budgeting, or call sheets.
Many writers keep both software active during a transition: Celtx for projects already deep in production planning, Laper for new scripts where AI and real-time collaboration are part of the workflow.
Try Laper
The Junior plan is free, no credit card required. If a fast, AI-native editor with real-time collaboration sounds like the writing experience you have been missing, the cost of finding out is zero.
For broader context, see our Final Draft alternative comparison and AI screenwriting software comparison 2026.