# CastReader vs Sider

CastReader records 55,999 monthly visits with +9.8% month-over-month growth and Freemium pricing. Sider records 2,644,740 monthly visits with -10.6% growth and Freemium pricing.

| Metric | [CastReader](https://openaitools.app/tool/castreader) | [Sider](https://openaitools.app/tool/sider) |
| :--- | :--- | :--- |
| Website URL | https://castreader.com | https://sider.ai |
| Categories | AI Text-to-Speech, AI Speech Synthesis, AI Reader | AI Assistant, AI Chatbot, AI Writing Assistants, AI Reader |
| Pricing Model | Freemium | Freemium |
| Monthly Visits | 55,999 | 2,644,740 |
| MoM Growth Rate | +9.8% | -10.6% |
| Primary Market | United States | United States |
| Direct Visits | 19,699 | 1,699,535 |
| Review Score | 4.4 | 4.5 |
| Saved Count | 0 | 31 |
| Supported Platforms | Website | Website |

## CastReader

CastReader is built for people who want to consume long-form text with their ears as well as their eyes. Once installed as a Chrome or Edge extension, or opened as an iPhone, iPad or Android app, it reads supported pages and documents aloud using natural AI voices while a word-synced highlight and auto-scroll keep your place. A public Voice Hub lets you preview real voice samples by language before committing, and playback speed ranges from standard rates up to 3x on the paid plan.

What separates it from a plain screen reader is a feature called Read & Explain. Instead of only pronouncing a dense or foreign-language paragraph, CastReader works out what it means and walks you through it in the language you know best, while an animated pen circles and underlines the relevant lines in the original text. That mix of eyes-on-page and ears-on-explanation is aimed at research papers, technical documentation, foreign-language news and other long reads where passive narration is not enough.

Sources are organised into four families: book platforms such as Kindle, WeRead, Google Play Books, Libby, Kobo and O'Reilly; articles and subscriptions including Medium, Substack, The Atlantic, The New Yorker and major newspapers; work documents and email such as Google Docs, Notion, Gmail and Google Drive; and AI conversations from ChatGPT, Claude, Gemini, DeepSeek and Kimi. CastReader also offers private voice cloning for your own documents and a developer Voice API for embedding cloned speech into applications. Free use needs no account, and payments are handled by Stripe.

**Pricing & Plans:** Freemium. Free plan: $0 forever with 20 minutes of listening per day, standard voices up to 1.25x speed, 3 AI explains per day, and 30,000 translation characters per day when signed in. Pro: $4.99/month or $35.99/year (about $3/month, 40% saving) removing the daily listening cap, unlocking full ebooks and long PDFs, more premium voices up to 3x speed, unlimited daily explains, 120 personal-voice minutes per membership month, and 3,000,000 translation characters per month. A 3-day free trial is available; billing is via Stripe.

- **Synced read-aloud:** Natural AI voices narrate webpages, PDFs, ebooks and documents while each spoken word is highlighted and the page auto-scrolls, so you never lose your place.
- **Read & Explain:** Instead of only reading a hard passage, CastReader summarises and unpacks its meaning in the language you know best, with an animated pen marking the key lines in the original text.
- **Wide source coverage:** Works across Kindle, WeRead, Google Play Books, O'Reilly and other book platforms, news and newsletter sites, Google Docs, Notion, Gmail, plus ChatGPT, Claude, Gemini, DeepSeek and Kimi answers.
- **Voice Hub and voice cloning:** Preview real samples of dozens of voices across many languages, and create private cloned voices that Pro members can apply to their own PDF, EPUB, Word and TXT files.
- **Developer Voice API:** A REST API for text-to-speech and private voice cloning in 10 languages, returning MP3 or WAV, priced at $8 per 1M characters for successful generations.

**Strengths:** Combines plain read-aloud with guided explanations that point back at the source text; Covers an unusually broad set of sources, from Kindle and Gmail to ChatGPT and Claude answers; Free tier is genuinely usable with no account required, and the 3-day Pro trial needs no commitment; Personal voice cloning and a pay-per-success Voice API extend it beyond a simple reader

**Limitations:** The 20-minute daily listening cap on the free plan runs out quickly for long books or PDFs; Source support and iOS previews vary by platform, browser version and content access rules; Applying a cloned voice to your own text is limited to 120 minutes per membership month even on Pro

[Profile (Markdown)](https://openaitools.app/tool/castreader.md)

## Sider

Sider's premise is that you should not have to leave the page you are reading to use an AI assistant. Its sidebar overlays the browser, detects the content in view, and responds with chat, summaries, translations or explanations using frontier models from multiple providers. The result is a lightweight research and reading workflow: highlight a paragraph, ask for a simpler explanation, translate a PDF and keep the original in sight.

Recent versions push Sider beyond chat. Sider Hand is a browser agent that works across real websites and uses your logged-in sessions to carry out multi-step jobs such as comparing prices while shopping, filling forms, doing cross-site research or triaging a Gmail inbox. Sider Code goes the other way, letting you instruct changes to a website's appearance or behaviour in plain language and preserving the customisation for next time. A Create module generates images, videos, slides and documents from the same panel.

Pricing moves from a limited free tier to credit-based paid plans aimed at heavier users. Lower plans suit occasional chat, summarisation and translation, while higher tiers add a dedicated cloud computer that keeps the browser agent running around the clock and a larger monthly credit allowance. Sider ships as browser extensions for Chrome and Edge plus desktop and mobile apps for macOS, Windows, iOS and Android, and is used by a very large installed base.

**Pricing & Plans:** Freemium. Free tier available with limited credits; paid plans advertised at roughly US$10/month for occasional use up to around US$100/month at the top tier, with higher credit allowances and a dedicated cloud computer on the upper plans.

- **AI sidebar on any page:** A persistent panel that reads the page you are on and answers follow-ups with GPT, Claude or Gemini without copying content into another tab.
- **Summarise and chat with documents:** Summarise long articles, PDFs and YouTube videos, extract key points, and ask detailed questions about the source material.
- **Translation and read-aloud:** Translate webpages, PDFs and images, compare bilingual output side by side, and have content read aloud for review on the move.
- **Sider Hand browser agent:** Delegate multi-step tasks across real websites — price comparison, form filling, research and inbox triage — using your existing logged-in sessions.
- **Sider Code page customisation:** Describe a change in plain words and have Sider restyle or simplify any website, remembering the modification for future visits.

**Strengths:** Works inside the browser you already use, with no context switching; Access to multiple frontier models from one subscription; Strong reading toolkit: PDF chat, YouTube summaries, translation and read-aloud; Increasingly capable agent features for multi-step browser tasks

**Limitations:** Useful credits run out quickly on the free and lower tiers; Model availability and quota rules change over time, so expectations must be checked per plan; Some agent and code features depend on a cloud machine and heavier plans

[Profile (Markdown)](https://openaitools.app/tool/sider.md)

## Frequently Asked Questions

### How do CastReader and Sider compare in monthly traffic?

CastReader has 55,999 monthly visits, while Sider has 2,644,740. Traffic estimates describe audience size, not product quality.

### How do their growth rates compare?

CastReader has a month-over-month growth rate of +9.8%; Sider has -10.6%.

### How does pricing compare?

CastReader: Freemium. Freemium. Free plan: $0 forever with 20 minutes of listening per day, standard voices up to 1.25x speed, 3 AI explains per day, and 30,000 translation characters per day when signed in. Pro: $4.99/month or $35.99/year (about $3/month, 40% saving) removing the daily listening cap, unlocking full ebooks and long PDFs, more premium voices up to 3x speed, unlimited daily explains, 120 personal-voice minutes per membership month, and 3,000,000 translation characters per month. A 3-day free trial is available; billing is via Stripe. Sider: Freemium. Freemium. Free tier available with limited credits; paid plans advertised at roughly US$10/month for occasional use up to around US$100/month at the top tier, with higher credit allowances and a dedicated cloud computer on the upper plans.

## Alternatives

| # | Tool Name | Monthly Visits | MoM Growth Rate | Pricing Model | Summary | Profile (Markdown) |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | [ChatGPT](https://openaitools.app/tool/chatgpt-4) | 6,048,022,723 | +2.2% | Freemium | OpenAI's flagship multimodal assistant powered by GPT-6 and GPT-5.6 for reasoning, coding, and deep research. | [.md](https://openaitools.app/tool/chatgpt-4.md) |
| 2 | [Claude](https://openaitools.app/tool/claude-2) | 1,253,439,413 | +23.8% | Freemium | Anthropic's frontier AI workspace powered by Claude 5.5 for agentic coding, analysis, and nuanced writing. | [.md](https://openaitools.app/tool/claude-2.md) |
| 3 | [Speechify](https://openaitools.app/tool/speechify) | 5,457,475 | +0.5% | Freemium | Text to speech and voice AI across every device | [.md](https://openaitools.app/tool/speechify.md) |
| 4 | [Monica](https://openaitools.app/tool/monica-ai) | 4,512,775 | -11.3% | Freemium | Offers a very similar browser sidebar experience with multiple AI models, but features slightly different pricing and workspace tools. | [.md](https://openaitools.app/tool/monica-ai.md) |
| 5 | [Luvvoice](https://openaitools.app/tool/luvvoice-free-text-to-speech) | 1,438,923 | -8.2% | Freemium | Free AI text to speech with 200+ voices in 70+ languages | [.md](https://openaitools.app/tool/luvvoice-free-text-to-speech.md) |
| 6 | [Merlin AI](https://openaitools.app/tool/merlin-ai) | 1,382,634 | +13.1% | Freemium | Provides robust browser-based summarization and prompt assistance, but lacks some of Sider's deeply integrated multi-model chat UI features. | [.md](https://openaitools.app/tool/merlin-ai.md) |
| 7 | [HARPA AI](https://openaitools.app/tool/harpa-ai) | 537,461 | +99.3% | Freemium | Excels at advanced web automation and data extraction alongside chat, but has a steeper learning curve than Sider. | [.md](https://openaitools.app/tool/harpa-ai.md) |
| 8 | [Peech: Text to Speech Reader](https://openaitools.app/tool/peech-text-to-speech-reader) | 353,093 | -26% | Freemium | Listen to anything. Beautifully. | [.md](https://openaitools.app/tool/peech-text-to-speech-reader.md) |
| 9 | [Glarity](https://openaitools.app/tool/glarity-summarize-google-and-youtube) | 188,823 | -49.6% | Freemium | Summarize YouTube, Google, and any page with AI — free in your browser | [.md](https://openaitools.app/tool/glarity-summarize-google-and-youtube.md) |
| 10 | [Kome AI](https://openaitools.app/tool/kome-ai) | 174,910 | -6.5% | Freemium | Integrates bookmark management and content composition into a clean sidebar, but has a more limited feature set than Sider. | [.md](https://openaitools.app/tool/kome-ai.md) |

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Source: https://openaitools.app/compare/castreader-vs-sider

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