# GPTZero Alternatives 2027: 14 Paid, Free & Open-Source

Source: https://zekaiwork.com/alternatives/gptzero/
Prices checked: 2026-11-13 (Zekai Price Ledger)

The best GPTZero alternatives in 2027 are Originality.ai (best overall, $12.95/mo billed yearly), Scribbr (best free plan: Unlimited free AI checks) and SlopTotal (best open source, MIT). GPTZero itself starts at $12.99/mo billed yearly. Zekai checked these prices on vendor pages on 13 Nov 2026; 11 more are compared below, including 5 with a free plan and 4 open source.

| Tool | Type | Starting price | Free plan limit | Licence | Best for | Price checked | Links |
|---|---|---|---|---|---|---|---|
| GPTZero (the tool being replaced) | — | $12.99/mo billed yearly | 10,000 words a month, 1 advanced scan | — | — | 2026-11-12 | [pricing](https://gptzero.me/pricing) |
| Copyleaks | Free plan + paid | $13.99/mo billed yearly | 25,000 characters per free scan; no free plan on pricing page | — | Plagiarism plus AI checks bought by credit | 2026-11-12 | [site](https://copyleaks.com) [pricing](https://copyleaks.com/pricing) [Zekai page](https://zekaiwork.com/ai-tools/copyleaks/) |
| Originality.ai | Free plan + paid | $12.95/mo billed yearly | 10K words (100 credits) one time; comparison table says 60 credits renewing daily | — | Bulk content checks for publishers and agencies | 2026-11-12 | [site](https://originality.ai) [pricing](https://originality.ai/pricing) [Zekai page](https://zekaiwork.com/ai-tools/originality-ai/) |
| Winston AI | Free plan + paid | $10/mo billed yearly | 2,000 credits, 14-day trial | — | Detecting AI text, images and deepfakes together | 2026-11-12 | [site](https://gowinston.ai) [pricing](https://gowinston.ai/pricing/) [Zekai page](https://zekaiwork.com/ai-tools/winston-ai/) |
| ZeroGPT | Free plan + paid | $8.99/mo billed yearly | 15,000 characters per AI detection | — | Quick free AI text checks with batch upload | 2026-11-12 | [site](https://www.zerogpt.com) [pricing](https://www.zerogpt.com/pricing) [Zekai page](https://zekaiwork.com/ai-tools/zerogpt/) |
| Quetext | Free plan + paid | $14.99/mo | AI detector up to 1,000 words; plagiarism checker up to 1,000 words | — | Plagiarism checker and AI detector bundle | 2026-11-12 | [site](https://www.quetext.com) [pricing](https://www.quetext.com/pricing) [Zekai page](https://zekaiwork.com/ai-tools/quetext/) |
| Isgen | Paid | $8/mo billed yearly | No free plan | — | Low-cost academic detector with plagiarism check | 2026-11-12 | [site](https://isgen.ai) [pricing](https://isgen.ai/pricing) [Zekai page](https://zekaiwork.com/ai-tools/isgen/) |
| Sapling | Free plan + paid | $25/mo | 2,000 characters per check, 5 files per batch | — | AI detector inside a writing-suggestions tool | 2026-11-12 | [site](https://sapling.ai) [pricing](https://sapling.ai/pricing) [Zekai page](https://zekaiwork.com/ai-tools/sapling/) |
| Scribbr | Free | Free plan; paid price not published | Unlimited free AI checks, no sign-up; word cap not stated | — | Students wanting a no-sign-up free check | 2026-11-12 | [site](https://www.scribbr.com) [pricing](https://www.scribbr.com/ai-detector/) [Zekai page](https://zekaiwork.com/ai-tools/scribbr/) |
| Turnitin | Paid | Not checked | No free plan | — | Institution-wide similarity and AI writing checks | 2026-11-12 | [site](https://www.turnitin.com) [pricing](https://turnitin.com/solutions/ai-writing) [Zekai page](https://zekaiwork.com/ai-tools/turnitin/) |
| SlopTotal | Open source | Free (self-hosted) | No limit (self-hosted) | MIT | Self-hosted multi-engine AI text detector | 2026-11-13 | [site](https://sloptotal.com) [code](https://github.com/pablocaeg/sloptotal) [Zekai page](https://zekaiwork.com/free-open-source/sloptotal/) |
| Binoculars | Open source | Free (self-hosted) | No limit (self-hosted) | BSD-3-Clause | Research-grade zero-shot detection you run yourself | 2026-11-13 | [site](https://github.com/ahans30/Binoculars) [code](https://github.com/ahans30/Binoculars) [Zekai page](https://zekaiwork.com/free-open-source/binoculars/) |
| Fast-DetectGPT | Open source | Free (self-hosted) | No limit (self-hosted) | MIT | Zero-shot detection from an ICLR 2024 paper | 2026-11-13 | [site](https://fastdetect.net/) [code](https://github.com/baoguangsheng/fast-detect-gpt) [Zekai page](https://zekaiwork.com/free-open-source/fast-detect-gpt/) |
| Open Detector | Open source | Free (self-hosted) | No limit (self-hosted) | MIT | Academic-paper AI detection with a small model | 2026-11-13 | [site](https://github.com/Imalwayshere/Open-Detector) [code](https://github.com/Imalwayshere/Open-Detector) [Zekai page](https://zekaiwork.com/free-open-source/open-detector/) |
| SynthID Text | Open source | Free (self-hosted) | No limit (self-hosted) | Apache-2.0 | Watermark detection for text you generate | 2026-11-13 | [site](https://github.com/google-deepmind/synthid-text) [code](https://github.com/google-deepmind/synthid-text) [Zekai page](https://zekaiwork.com/free-open-source/synthid-text/) |

## How each alternative compares with GPTZero

- **Copyleaks** (Free plan + paid, $13.99/mo billed yearly, checked 2026-11-12): Sells by credit: Personal gives 100 credits a month, one credit covering up to 250 words or 1 image; Pro adds 25 seats and website scanning by sitemap, which GPTZero's page does not list. Switch if you scan by document count, need image detection or whole-site sitemap scans, and prefer credits over a monthly word quota. Stay with GPTZero if you want a free recurring word quota and a single flat plan with batch upload up to 250 files.
- **Originality.ai** (Free plan + paid, $12.95/mo billed yearly, checked 2026-11-12): Pro gives 200K words (2K credits) a month with 30-day scan history, bulk scan, PDF download and paid extra seats at $8.62 a month; GPTZero Premium gives 300,000 words but no extra team seats. Switch if you vet freelancer or agency articles in bulk and want scan history, shareable reports and add-on seats. Stay with GPTZero if you check single essays and want a free quota that resets monthly instead of a one-time allowance.
- **Winston AI** (Free plan + paid, $10/mo billed yearly, checked 2026-11-12): Credit-based: Essential gives 100,000 credits a month and covers AI image and deepfake detection, OCR for scans and handwriting, plagiarism checks and shareable PDF reports; Advanced adds 5 team members. Switch if you also screen images, deepfakes or scanned handwriting and want a 5-member team plan. Stay with GPTZero if you want a free plan that does not expire after 14 days.
- **ZeroGPT** (Free plan + paid, $8.99/mo billed yearly, checked 2026-11-12): Free forever at $0 with 15,000 characters per detection; Pro lifts it to 100,000 characters and 50 batch files and adds an AI video detector, summarizer and a WhatsApp or Telegram bot. Switch if you want a cheaper paid tier and extras such as a video detector and WhatsApp access. Stay with GPTZero if you rely on sentence-level highlighting and per-model detection in one report.
- **Quetext** (Free plan + paid, $14.99/mo, checked 2026-11-12): Essential bundles a plagiarism checker and AI detector on 100k words a month, plus a humanizer, summarizer, API access and 20-file bulk upload; the free AI detector stops at 1,000 words. Switch if you want plagiarism and AI checks in one allowance and API access at a lower entry price. Stay with GPTZero if you check longer texts, since Quetext's free detector stops at 1,000 words.
- **Isgen** (Paid, $8/mo billed yearly, checked 2026-11-12): Academic plan is $8 a month billed yearly ($14 monthly) for 350,000 detection words a month, phrase-level analysis, a plagiarism checker, 60,000 characters per submission and 15 days of history. Switch if you want a lower price than GPTZero Premium with phrase-level analysis and plagiarism checks. Stay with GPTZero if you need LMS integration with Canvas or Google Classroom and a free tier with a recurring quota.
- **Sapling** (Free plan + paid, $25/mo, checked 2026-11-12): Free detector checks stop at 2,000 characters; Pro raises that to 100,000 characters and 10 files per batch and adds writing suggestions plus a usage-billed API ($5 minimum). Switch if you want AI detection beside a grammar and rewrite assistant or a pay-as-you-go detection API. Stay with GPTZero if you scan full essays and want 10,000 words a month free instead of a 2,000-character cap.
- **Scribbr** (Free, Free plan; paid price not published): Advertises unlimited free AI checks with no sign-up and a separate Premium AI Detector; the page states no word cap and no published Premium price. Switch if you want unlimited quick checks without an account and do not need reports or an API. Stay with GPTZero if you need a stated word quota, Chrome extension and LMS integrations behind a login.
- **Turnitin** (Paid, Not checked): Sold to institutions through sales with LMS integration; its AI writing detection is described as available with Originality, and no price or free tier is published. Switch if your school or university buys centrally and needs LMS-integrated similarity plus AI reports. Stay with GPTZero if you are an individual or small team who needs a published price you can start on today.
- **SlopTotal** (Open source, Free (self-hosted)): Runs 23 detection engines, including Binoculars and Fast-DetectGPT, on your own CPU and returns one calibrated score with per-engine votes, file and URL scanning, and a JSON API. Switch if you want to see each detector engine's vote instead of a single number. Stay with GPTZero if you cannot spare about 8 GB of RAM for the detector models.
- **Binoculars** (Open source, Free (self-hosted)): Zero-shot detector needing no training data; it scores text with two Falcon-7B models locally and returns a score, without sentence highlighting or a web dashboard. Switch if you want to run detection locally on your own text and keep documents off a vendor server. Stay with GPTZero if you want a web page with highlighted sentences and batch upload ready today.
- **Fast-DetectGPT** (Open source, Free (self-hosted)): ICLR 2024 zero-shot method using conditional probability curvature; the README reports 0.9887 AUROC on five-model generations and ships a local script, with no dashboard or upload. Switch if you need to score text on your own machine with a method you can inspect. Stay with GPTZero if you need sentence highlighting and batch upload rather than a command-line score.
- **Open Detector** (Open source, Free (self-hosted)): BERT-base classifier trained for academic papers; the README claims 99.57% accuracy on its own dataset and says it is stylometric only. It is a model and script, not a web app. Switch if you want a small classifier you can load in a few lines of Python. Stay with GPTZero if you want sentence-level highlighting and downloadable reports from the tool itself.
- **SynthID Text** (Open source, Free (self-hosted)): Google DeepMind reference code that detects only text carrying its SynthID watermark; the frequentist detector gives a binomial p-value for a key, so it cannot flag unwatermarked ChatGPT or Claude output. Switch if you want to study watermark detection with Google's reference code and a p-value. Stay with GPTZero if you want a production service; the repo calls itself a reference implementation only.

## Open-source options in detail

- **SlopTotal** (https://github.com/pablocaeg/sloptotal): Licence: MIT; Commercial use: Yes (MIT).; Runs on: Runs on CPU; loaded models need about 8.3 GB of RAM; GPU optional.; Setup: moderate: One docker run command; models download on first start.; Last commit: 2026-11-03; Last release: 2026-11-03; GitHub stars: 114 (2026-11-13)
- **Binoculars** (https://github.com/ahans30/Binoculars): Licence: BSD-3-Clause; Commercial use: Yes for the code (BSD-3-Clause); check the licence of the Falcon models you download.; Runs on: Python 3.9; two 7B models, so a GPU or large-memory machine.; Setup: hard: Clone the repo, pip install, then download two 7B models.; Last commit: 2024-05-14; GitHub stars: 435 (2026-11-13)
- **Fast-DetectGPT** (https://github.com/baoguangsheng/fast-detect-gpt): Licence: MIT; Commercial use: Yes (MIT).; Runs on: Authors ran it on an 80 GB A100; the local demo defaults to gpt-neo-2.7B.; Setup: hard: Python 3.8 and PyTorch 1.10 environment plus model downloads.; Last commit: 2026-02-07; GitHub stars: 440 (2026-11-13)
- **Open Detector** (https://github.com/Imalwayshere/Open-Detector): Licence: MIT; Commercial use: Yes (MIT); the Hugging Face model card also states MIT.; Runs on: Python with PyTorch and Transformers; BERT-base model, 512-token input.; Setup: moderate: pip install transformers torch, then a short Python script.; Last commit: 2026-11-12; GitHub stars: 254 (2026-11-13)
- **SynthID Text** (https://github.com/google-deepmind/synthid-text): Licence: Apache-2.0; Commercial use: Yes (Apache-2.0), but the repo calls itself a reference implementation, not for production.; Runs on: Any GPU such as a T4 for Gemma 3 270M; GPT-2 runs on CPU.; Setup: moderate: Python virtual environment and a Jupyter notebook from the repo.; Last commit: 2026-10-26; GitHub stars: 1,300 (2026-11-13)

## Questions

### What is the best alternative to GPTZero in 2027?
Originality.ai is the best overall GPTZero alternative on this page ($12.95/mo billed yearly). For no cost, Scribbr has a free plan (Unlimited free AI checks, no sign-up; word cap not stated). To self-host, SlopTotal is open source (MIT).

### Is there a free version of GPTZero?
Yes. GPTZero has a free plan: 10,000 words a month, 1 advanced scan. Paid plans start at $12.99/mo billed yearly, checked on 12 Nov 2026.

### Is there a 100% free alternative to GPTZero?
Yes. SlopTotal, Binoculars, Fast-DetectGPT, Open Detector, SynthID Text are open source and free to self-host. Copyleaks, Originality.ai, Winston AI, ZeroGPT, Quetext, Sapling, Scribbr have a free plan with limits, shown in the table.

### What is cheaper than GPTZero?
Isgen starts at $8/mo billed yearly, against $12.99/mo billed yearly for GPTZero, as listed on each vendor's pricing page on 12 Nov 2026.

### How much do GPTZero alternatives cost for a team of 5?
If each of 5 people buys the entry paid plan, at the prices Zekai checked on 13 Nov 2026, the monthly cost is Isgen $40/mo, ZeroGPT $44.95/mo, Winston AI $50/mo, against GPTZero $64.95/mo for GPTZero. Team and business plans can cost more per seat. The Zekai Cost Finder on this page recalculates for any team size.

### Which is better, Originality.ai or GPTZero?
Pro gives 200K words (2K credits) a month with 30-day scan history, bulk scan, PDF download and paid extra seats at $8.62 a month; GPTZero Premium gives 300,000 words but no extra team seats. Choose Originality.ai if you vet freelancer or agency articles in bulk and want scan history, shareable reports and add-on seats. Stay with GPTZero if you check single essays and want a free quota that resets monthly instead of a one-time allowance.

### Why are people leaving GPTZero?
The documented reasons are: Premium costs $23.99 a month billed monthly versus $12.99 a month billed annually, and Professional is $45.99 monthly versus $24.99 annually; the page advertises a 45% annual saving (12 Nov 2026); The Free plan is capped at 10,000 words a month with 1 advanced scan; Premium raises that to 300,000 words a month and 50,000 characters per scan, and plagiarism checking and page-by-page scanning sit only in higher tiers (12 Nov 2026). Each is sourced in the section above.

### What is better than GPTZero?
It depends on the job: Originality.ai for bulk publisher checks, Winston AI for images and deepfakes, Copyleaks for credit-based plagiarism checks, Turnitin for institutions.

## Related on Zekai

- [Copyleaks alternatives](https://zekaiwork.com/alternatives/copyleaks/)
- [Winston AI alternatives](https://zekaiwork.com/alternatives/winston-ai/)
- [ZeroGPT alternatives](https://zekaiwork.com/alternatives/zerogpt/)
- [Turnitin alternatives](https://zekaiwork.com/alternatives/turnitin/)
- [AI for Education & E-learning](https://zekaiwork.com/professions/ai-education-elearning-teaching-tools/)

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Live table, team cost finder and price alerts: https://zekaiwork.com/alternatives/gptzero/