Hy4 preview vs Synthesia: Features, Pricing & Which Is Better (2026)
A side-by-side comparison of Hy4 preview and Synthesia — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.
Hy4 preview
Tencent
Tencent's open-weight Hy4 preview, a 770B-parameter Mixture-of-Experts model with 49B active parameters and a 1M-token context window.
Key features
- 770B Mixture-of-Experts Architecture: Holds 770 billion total parameters while activating only 49 billion per token, so capacity scales without proportional inference cost.
- 1M-Token Context Window: Accepts inputs exceeding one million tokens, allowing whole codebases, long document sets or extended agent traces in a single prompt.
- Apache 2.0 Open Weights: Released under a permissive licence that allows commercial use, modification and redistribution with no separate agreement.
- Productivity Task Focus: Tuned for real-world coding, office work and scientific research rather than narrow benchmark optimisation.
- Multi-Product Availability: Accessible globally through Tencent's WorkBuddy, CodeBuddy, Yuanbao and ima applications in addition to the raw weights.
- API Access via TokenHub and OpenRouter: Can be called through Tencent Cloud TokenHub or OpenRouter for teams that prefer hosted inference over self-hosting.
Best for
- Whole-Repository Code Work: Load an entire codebase into the million-token context to reason about refactors and cross-file dependencies at once.
- Long-Horizon Agent Tasks: Drive multi-step agent workflows where the full history of tool calls and intermediate results must stay in context.
- Self-Hosted Deployment: Run a frontier-scale open-weight model on private infrastructure where data cannot leave the organisation.
- Scientific Literature Analysis: Ingest large collections of papers or experimental logs and synthesise findings without chunking the input.
- Office Document Processing: Summarise, draft and restructure long reports, contracts and spreadsheets in enterprise workflows.
- Commercial Fine-Tuning: Adapt the weights for a proprietary product under the Apache 2.0 licence without negotiating a model licence.
Synthesia
Synthesia
Create professional AI-generated videos from text using realistic avatars and voiceovers in 140+ languages.
Key features
- Text-to-Video Generation: Convert written scripts into complete videos by mapping text to avatar speech, timing, and on-screen text, enabling fast video creation without recording equipment.
- Advanced AI Avatars: Choose from a library of customizable on-screen presenters (avatars) that deliver scripts with natural facial expressions and gestures to create professional-looking presenter-led content.
- Multilingual Voiceovers: Generate natural-sounding synthesized voiceovers across 140+ languages and accents to localize content and reach global audiences without re-recording.
- Template Library & Scene Builder: Use pre-built, industry-specific templates and a drag-and-drop scene editor to assemble videos quickly, applying consistent branding, layouts, and visuals.
- Cost and Time Efficiency: Replace traditional production workflows (talent, studio, editing) with an automated creation pipeline that significantly reduces per-video time and production costs.
- Metadata & File Support: Export and manage video assets and associated metadata (e.g., .synthesia metadata files via supporting tools) to integrate with existing content workflows and versioning.
- Text-to-video generation with realistic AI avatars
- 140+ language voiceovers and TTS
- Web-based Studio editor with templates
- Pre-built and (paid) custom avatars
- Team/enterprise features (SSO, account management, compliance)
- API access (reported to require paid plan)
- Export at up to 1080p (reported)
- Generate videos from plain text scripts using AI avatars
- Natural-sounding voiceovers / text-to-speech in 140+ languages
- Library of pre-built avatars (40+ mentioned across sources) and option to create custom avatars
- Template-driven video design and production workflow
- Download, stream, and translate generated videos
- Localization support for creating region/language-specific content
- Desktop components: Mac desktop app and a Metadata Editor for .synthesia files
- Synthesia metadata file format (.synthesia) for content metadata and editing
- Metadata Editor requires .NET Framework 4.8 on Windows
Best for
- Employee Training & Onboarding: Produce scalable training modules and onboarding videos with consistent messaging, translated into multiple languages for global teams.
- Marketing & Product Videos: Rapidly create promotional videos, product explainers, and ads using branded templates and avatar presenters without hiring actors or studios.
- Internal Communications: Deliver CEO messages, policy updates, and corporate announcements as short, polished videos to increase engagement across distributed workforces.
- E-learning & Course Content: Build narrated course lessons and explainer videos with synchronized on-screen text and avatars to improve learner retention.
- Localized Content at Scale: Generate localized versions of the same video in dozens of languages to support international campaigns and markets.
- Demo & Sales Enablement: Produce quick product demos and sales enablement videos tailored to different regions or verticals without repeated shoots.
- Corporate training and e-learning videos
- Sales and marketing video content
- Internal communications and presentations
- Localized/multilingual video production at scale
- Rapid prototype and explainer videos without production crew
- Corporate training and internal communications with localized presenters
- E-learning course creation with multilingual narration and avatars
- Marketing and promotional videos produced without cameras or actors
- Rapid production of localized content for global audiences
- Social media and product explainer videos created from scripts