Sherlock
Natural-language event parser for JavaScript
If you need a zero-dependency, client-side natural language date parser for your web app, Sherlock is a solid pick. It's not a full calendar solution, but for parsing event phrases, it does one job well.
- JavaScript developers building calendar UIs
- Product teams adding smart scheduling inputs
- Hobbyist coders creating personal assistant bots
- Open source contributors interested in NLP
- Enterprise applications requiring high accuracy
- Non-developers looking for a ready-made calendar app
- Projects needing multilingual support (English only)
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In short
Sherlock — Natural-language event parser for JavaScript. Best for JavaScript developers building calendar UIs, Product teams adding smart scheduling inputs, Hobbyist coders creating personal assistant bots. Free to use.
Viability Score
How likely is Sherlock to still be operational in 12 months? Based on 4 signals — momentum (how recently it shipped), wrapper dependency, revenue model, and web presence.
Last calculated: July 2026
How we score →Key Features
- Parse natural language dates like 'next Monday'
- Extract event titles from phrases
- Support for relative dates (e.g., 'in 4 weeks')
- Handle time ranges (e.g., 'from Jan 12 - 29')
- Recognize holidays (e.g., 'Christmas')
- Recurring event support (e.g., 'every week')
- Client-side processing, no server needed
- Zero external dependencies
- Open source (MIT license)
- Small footprint (minified under 10KB)
About Sherlock
Sherlock is a lightweight JavaScript library that converts natural language date and time expressions into structured calendar events. It allows developers to parse phrases like "next Monday at 3pm" or "vacation in 4 weeks" into start and end dates, titles, and other event fields. The library is designed for anyone building scheduling, calendaring, or reminder features in web applications. Sherlock works entirely client-side, making it fast and privacy-friendly. What sets Sherlock apart is its focus on natural language understanding for events, using a rule-based approach rather than an external API. It supports recurring events, relative dates, and time ranges. The demo on the homepage shows instant parsing with examples, and the source code is available for inspection and contribution. Sherlock is open source (MIT license) and has no dependencies.
Behind the Verdict
Sherlock fills a narrow but useful niche: turning human-written date/time phrases into structured event data. For JavaScript developers building scheduling UIs, it's a clean, lightweight library that works offline and requires no external API calls. The rule-based approach keeps it fast and predictable, though it lacks the flexibility of NLP-powered alternatives. Compared to libraries like chrono-node, Sherlock is simpler and smaller (under 10KB minified). However, it's English-only and doesn't handle ambiguous language as well as more sophisticated parsers. Open source (MIT) means you can fork and customize. We'd reach for this when we want a quick, dependency-free way to add smart date input to a form. Where it falls short: no support for timezones or fuzzy partial dates (e.g., "next week" without a day). If your app only needs to parse English event strings client-side, Sherlock is a great fit.
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Use Cases
- Parse user input like 'meeting next Tuesday at 2pm' into a calendar event
- Build a natural language interface for scheduling reminders
- Automatically extract event details from text in a messaging app
- Enable voice commands for calendar creation
- Convert free-text date ranges into start and end dates for booking systems
Limitations
- Sherlock uses rule-based parsing, which may miss ambiguous or complex date expressions.
- It does not support time zones or recurring events beyond basic patterns.
- Performance is fine for short phrases but not tested for very large inputs.
12-month cost
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Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
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