AI video tools fall into two camps, and mixing them up is the most common mistake. Runway, Google Veo and Kling generate cinematic clips from text or images. HeyGen and Synthesia make presenter-style videos with AI avatars. Runway is the best all-round creative toolkit, Google’s Flow is good for short clips with audio if you already pay for Google AI, Kling is the budget pick with longer clips, HeyGen suits marketers who need presenter videos in many languages, and Synthesia suits training and internal content. One more note: OpenAI’s Sora is no longer an option, which we cover below.
Disclosure. The buttons in this guide link to each tool’s official site. If we join a tool’s affiliate program later, those links may earn us a commission at no extra cost to you, and that won’t change how we rank anything. See our affiliate disclosure.
Quick comparison
| Tool | Best for | Free option | Main advantage | Biggest drawback | Pricing reference |
|---|---|---|---|---|---|
| Runway | Creative teams generating and editing clips | 125 one-time credits, watermarked | Generation plus editing in one place | Credits run out fast | From $15/mo |
| Google Veo / Gemini Omni | Short clips with native audio | 50 daily Flow credits | Audio built in, cheap entry plan | Short clips, product names changing | From $4.99/mo |
| Kling AI | Budget creators wanting longer clips | Daily credits, watermarked | 3 to 15 second clips with audio | Pricing and commercial terms hard to confirm | See Kling membership |
| HeyGen | Presenter videos and translation | 3 videos a month, 1 minute each | Many languages, voice cloning | Commercial terms unclear on public pages | From $29/mo |
| Synthesia | Training and business explainers | Yes, with watermark | Strong consent controls, 140+ languages | Stock avatars can’t be used in paid ads | Starter $29/mo |
Two kinds of AI video
Generative clips (Runway, Veo, Kling) turn a prompt or still image into a few seconds of footage. They’re good for b-roll, concept visuals and social loops, and they’re not good at long, consistent stories. Avatar videos (HeyGen, Synthesia) put a digital presenter in front of a script. They’re good for explainers, onboarding and multilingual updates, and they look noticeably more corporate. Decide which one you need first, because the prices and rules are completely different.
What happened to Sora?
OpenAI’s help center says the Sora web and app experiences were discontinued on April 26, 2026, and the Sora API ends on September 24, 2026. If an older article recommends it, treat that as outdated.
The tools, reviewed
1. Runway: the creative toolkit
Runway generates video from text and images and edits existing footage, with an in-browser editor on top. The free plan gives 125 one-time credits and 5GB of storage, and free videos carry a Runway watermark. The pricing page lists Standard at $15 a month ($12 on annual billing) with 625 credits, Pro at $35 ($28) with 2,250 credits and Max at $95 ($76) with 9,500 credits. Standard and above remove the watermark.
Credits go quickly. Runway’s Gen-4.5 costs 60 credits for a 5-second clip, so Standard’s 625 credits cover about ten of those. Max clip length and resolution weren’t clear on the pages we read. Runway’s help article says you keep ownership of what you create and that Runway adds no non-commercial restriction, though it doesn’t say whether that varies by plan.
Pick it if you want to generate and edit clips in one place and can budget for credits.
2. Google Veo and Gemini Omni (Flow)
Google generates video through Gemini and its Flow tool. Its Gemini page says Gemini Omni will replace Veo in the Gemini app, while Flow’s credit table still lists Veo 3.1 models, so names are in flux. Without a subscription, Flow gives 50 credits a day, though video generation may be unavailable at peak times. Google AI Plus is $4.99 a month with 200 credits, AI Pro is $19.99 with 1,000 and AI Ultra starts at $99.99 with 10,000, on Google’s subscriptions page.
Veo clips run 4, 6 or 8 seconds, and the Gemini app’s Omni video goes up to 10 seconds, with native audio. All outputs carry an invisible SynthID watermark, and a visible one can be toggled in the profile menu (it’s automatic in India, South Korea and Vietnam). Google says it won’t claim ownership of your original content, but we couldn’t find a plan-by-plan commercial-use statement, so read the Flow terms before using clips in ads.
Pick it if you want short clips with sound and already pay for Google AI.
3. Kling AI: longer clips for less
Kling makes text-to-video and image-to-video clips, and Kling 3.0 clips run 3 to 15 seconds with native audio and lip-sync. Its own credit guide shows Standard at $6.99 for 660 credits, Pro at $25.99 for 3,000, Premier at $64.99 for 8,000 and Ultra at $127.99 for 26,000, with renewal prices higher than the first month’s. Because we couldn’t load the live membership page, treat these as indicative.
The free tier is watermarked, and one Kling page says free content isn’t for commercial use. Memberships remove the watermark. We couldn’t confirm paid-plan commercial terms, so check Kling’s terms of service before client work.
Pick it if you want long clips at a low cost and you’re comfortable verifying terms yourself.
4. HeyGen: presenter videos and translation
HeyGen creates avatar videos and translates or dubs existing ones with lip-sync. The free plan includes 3 videos a month, up to a minute each, with 500-plus stock avatars. The pricing page lists Creator at $29 a month (its FAQ cites $24 on annual billing) with 600 credits, Pro from $49 and Business at $149 plus $20 a seat. Paid plans support 175-plus languages versus 30-plus on Free.
HeyGen requires you to have legal rights and explicit consent for anyone whose likeness you use, but doesn’t describe how that’s technically enforced. Only the Enterprise plan lists commercial terms on the pricing page, so ask about commercial use before building a campaign on it.
Pick it if you create presenter-style marketing videos and need them in many languages.
5. Synthesia: training and business explainers
Synthesia has a free Basic plan with 500 credits a month, 10 video minutes, 9 avatars and a watermark. Starter is $29 a month with 1,250 credits (about 12 minutes of video), and Pro is $89 with 6,000 credits (about 60 minutes), with watermarks removed from Starter up. The page mentions yearly savings but doesn’t list yearly prices. Output is Full HD, and it supports 140-plus languages.
The restriction that matters for marketers: Synthesia’s licensing article allows stock avatars in training videos, FAQs and organic posts on YouTube and social media, but not in paid ads on platforms like Facebook, Instagram, YouTube or TikTok. Custom avatars require the depicted person’s informed consent, with a live consent recording for personal avatars.
Pick it if you make training, onboarding or internal videos and want strong consent controls.
Choose by job to be done
| If you need… | Start with | Why |
|---|---|---|
| B-roll and creative concept clips | Runway or Veo | Generative footage |
| The lowest cost per clip | Kling | Cheap entry plan, longer clips |
| A presenter video in several languages | HeyGen | Avatars and translation |
| Training and internal comms | Synthesia | Consent controls, business focus |
| Short clips with audio, already on Google AI | Google Flow | Included in your plan |
Free plans: what you really get
Free tiers exist to test, not to produce. Runway’s is a one-time credit pack with a watermark, Kling’s is watermarked and described as non-commercial, HeyGen allows three one-minute videos a month, and Synthesia’s includes a watermark too. Google’s Flow gives daily credits but may be unavailable at peak hours. Budget for a paid plan if you want clean, publishable output.
Rules marketers should know
- Likeness and consent: HeyGen and Synthesia both require consent from anyone whose face or voice you use.
- Ad restrictions: Synthesia’s stock avatars can’t be used in paid ads.
- Disclosure: platforms and local laws increasingly ask you to label AI-generated video. Check each platform’s rules before you post.
- Watermarks: free outputs are usually watermarked, and Google adds an invisible SynthID mark to everything.
For scripts and captions, see our guide to AI writing tools for small business.
Mistakes to avoid
- Choosing a generative tool when you really need a presenter, or the other way around.
- Not counting credits per clip. A plan that sounds big can cover only a handful of videos.
- Publishing free-tier output with a watermark or without commercial rights.
- Using someone’s face or voice without written consent.
- Expecting minute-long, consistent story videos from tools built for short clips.
FAQs
What is the best AI video generator for marketing?
For creative clips, Runway. For presenter-style videos, HeyGen. Both need paid plans for clean, publishable output.
Is there a free AI video generator?
Runway, Kling, HeyGen, Synthesia and Google Flow all have free options with limits, and most add a watermark.
Is Sora still available?
No. OpenAI discontinued the Sora web and app experiences on April 26, 2026, and the API ends September 24, 2026.
Can I use AI video in paid ads?
It depends on the tool. Synthesia’s stock avatars are barred from paid ads, and Kling’s and HeyGen’s commercial terms need checking. Read the licence for your plan.
How long can AI video clips be?
Generative tools produce short clips, typically a few seconds up to about 15 for Kling’s newest model. Avatar tools handle longer videos, with HeyGen paid plans listing 30-minute or longer videos.
Final verdict
Choose Runway if you want a creative toolkit, Google Flow for short clips with audio on a small budget, and Kling for long clips at a low price once you’ve confirmed its terms. Choose HeyGen for marketing presenters and Synthesia for training content. Start on a free tier, count credits per clip, and read the commercial-use terms before anything goes into a paid campaign.
More guides: Best Software and Canva alternatives.
