Label Sleuth is live · free · last verified 24 Oct 2026 · viability monitor
Label Sleuth
Open-source, no-code system from IBM Research for labeling text and training custom text classifiers without AI expertise.
If you are a domain expert with text data and no ML team, Label Sleuth is the cheapest credible route from raw examples to a working classifier: install it, label, and let active learning plus background training do the heavy lifting. It is particularly strong for sensitive legal, clinical and social-science text because it runs entirely on your own machine. It is not a managed product — you run Anaconda, Python and the maintenance yourself. If what you actually need is a hosted annotation service with vendor support, budget for a commercial platform instead; if budget is zero and privacy matters, start here.
Verdict generatedVerified 6d ago · liveness 53/100 · cite: rightaichoice.com/tools/label-sleuth
- Domain experts building text classifiers without coding (physicians, lawyers, psychologists)
- NLP researchers prototyping classification models quickly
- Small expert teams without ML engineers
- Legal, healthcare and social science projects handling sensitive text
- Teams that need a managed cloud service and do not want to install anything
- Projects annotating images, audio or video rather than text
- Organizations that require vendor SLAs and contracted support
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Skip Label Sleuth if you want a hosted annotation service someone else installs, scales and supports, or if your data is images, audio or video rather than text.
Background model training runs on your own machine, so the compute cost lands on your hardware and you feel it as slower labeling sessions on large datasets.
Label Sleuth is open source with no license fee, which puts it below commercial annotation platforms that charge per seat or per labeled item. The savings are offset by the cost of running and maintaining it yourself, so it suits researchers, individual experts and small teams rather than organizations that would bill internal engineering time against a support contract.
In short
Label Sleuth — Open-source, no-code system from IBM Research for labeling text and training custom text classifiers without AI expertise. Best for Domain experts building text classifiers without coding (physicians, lawyers, psychologists), NLP researchers prototyping classification models quickly, Small expert teams without ML engineers. Free to use.
What is Label Sleuth?
Label Sleuth — Open-source, no-code system from IBM Research for labeling text and training custom text classifiers without AI expertise. Best for Domain experts building text classifiers without coding (physicians, lawyers, psychologists), NLP researchers prototyping classification models quickly, Small expert teams without ML engineers. Free to use.
Label Sleuth is a free, open-source no-code system for text annotation and building text classifiers. It is aimed at domain experts — physicians, lawyers, psychologists, social scientists — who know their text data but have no machine learning background, and who would otherwise need an NLP specialist to turn that data into a working model. The workflow is deliberately plain: you install it locally with Anaconda and pip, start it, and open it in your browser at localhost, where an intuitive labeling UI lets you mark up examples while machine learning models train automatically in the background. Active learning decides which examples are most worth your time next, so you spend fewer labels reaching a usable classifier; the tool then serves real-time predictions on new text as you go. Label Sleuth was initiated by IBM Research together with academic collaborators, and the project's publications come from work in human-computer interaction, NLP and AI. It is extensible by design, so new model architectures or active learning strategies can be plugged in, and it exposes a REST API plus documented model training, active learning and system configuration options. Typical uses documented by the project are identifying contract clauses such as warranty terms in legal documents, flagging bullying content in large sets of text messages, and classifying customer interactions by request type or sentiment. Because it runs locally, your data stays on your own machine — a meaningful advantage for clinical or legal text you cannot upload to a third party. The trade-offs are equally clear: you supply the Python environment, the compute and the maintenance, and help comes from documentation, publications and the community Slack rather than a support contract.
Key features
- Intuitive no-code text annotation UI for domain experts
- Automatic machine learning model training in the background while you label
- Active-learning-driven guidance on which examples to label next
- Real-time model predictions shown during labeling
- Documented model training configuration
- Documented active learning configuration
- System configuration options
- Extensible architecture for adding model architectures and active learning techniques
- REST API for integration with other systems
- Local deployment so text data stays on your own machine
- Installation via Anaconda and pip in a dedicated Python environment
- Guided tutorial for quick start
- Language support documentation
- Browser-based access at localhost
- Open source project on GitHub with an open contribution process
Our long-form take written Jul 28, 2026 is more than 90 days old, so it is being re-reviewed against current data and is not shown.
Limitations
- You install and run Label Sleuth yourself.
- The documented setup is a four-step command-line procedure: install Anaconda, create and activate a Python 3.9 environment, run pip install label-sleuth, then start it and open it in your browser at localhost.
- Because it runs locally, you are responsible for the machine, the compute for background model training, upgrades and any scaling.
- Help comes from the project's documentation, its published research and the community Slack rather than a support contract.
- The tool is scoped to text classification; the project documents legal clause detection, bullying detection in messages and customer care analytics as its example workloads.
as of 2026-10-04
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Is Label Sleuth still active?
Label Sleuth is live · free · last verified 24 Oct 2026 · viability monitor.
Viability score
How well maintained and how widely used is Label Sleuth? Built from what the vendor actually publishes (docs, changelog, tutorials, integrations, pricing), whether the site is live, and how much real users discuss it. How we calculate this
Last calculated: October 2026
How we score →What do users say about Label Sleuth?
What people actually say about Label Sleuth — is it worth it?
Our community sentiment research written Jul 5, 2026 is more than 90 days old, so it is being re-reviewed against current data and is not shown.
How we verified this
Every listed fact about Label Sleuth— pricing, features, links, status — is re-read from the vendor's own pages by our verification pipeline and each change is logged with a date; the last pass ran on 24 Oct 2026. Pages mix model-assisted synthesis with human review; see how we verify.
Verification history
We have re-verified Label Sleuth 11 times since . Each pass re-reads the vendor's own pages and re-checks every listed field against that evidence; passes where nothing had changed are marked as such.
- — changed who it suits, description, hidden costs, limitations, switching in, switching out, who should skip it, pricing tiers, pricing fit, setup time, summary, use cases, our verdict, features
- — changed domain expiry
- — changed switching out, who should skip it, features, setup time, hidden costs, pricing fit, switching in, description
- — changed SSL certificate
- — changed pricing page
Showing the 5 most recent of 11 verification passes.
Free to cite with attribution — this page re-verifies continuously.
How much does Label Sleuth cost in 2026?
Label Sleuth: Free to use. Pricing last verified 24 Oct 2026.
12-month cost
Project the real annual outlay, including the implied monthly cost when only an annual tier is published.
Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
Where the pricing makes sense
The company stage and team size where Label Sleuth's pricing actually pencils out — and where peers do it cheaper.
Label Sleuth is open source with no license fee, which puts it below commercial annotation platforms that charge per seat or per labeled item. The savings are offset by the cost of running and maintaining it yourself, so it suits researchers, individual experts and small teams rather than organizations that would bill internal engineering time against a support contract.
Has Label Sleuth's pricing changed?
No plan price for Label Sleuth has moved since we began logging in Aug 2026; the pricing page is re-read on every verification pass.
Who should pick Label Sleuth?
Pick Label Sleuth if you are Domain experts building text classifiers without coding (physicians, lawyers, psychologists), NLP researchers prototyping classification models quickly, Small expert teams without ML engineers, Legal, healthcare and social science projects handling sensitive text.
Look elsewhere if you are Teams that need a managed cloud service and do not want to install anything, Projects annotating images, audio or video rather than text, Organizations that require vendor SLAs and contracted support, Large-scale enterprise deployments needing someone else to run and scale the system.
Skip it if Skip Label Sleuth if you want a hosted annotation service someone else installs, scales and supports, or if your data is images, audio or video rather than text.
GeneratedReal-world workflow fit
Concrete scenarios for the personas Label Sleuth actually fits — and what changes day-one when you adopt it.
Install Anaconda, create the label-sleuth Python environment, pip install label-sleuth, then open localhost:8000 and follow the guided tutorial. Start labeling warranty clauses you already know, watch predictions appear as the model trains in the background, and let active learning point you at the ambiguous contracts next.
Outcome: A working warranty-clause classifier built inside a few hours, trained on contracts that never left the machine.
Work through the tutorial to define a bullying category, label a seed set of messages, and use active-learning suggestions to prioritize the messages most likely to change the model.
Outcome: A reusable labeling scheme and a classifier that can be run over the wider message corpus to size up the problem.
Define several label dimensions for customer interactions — request type and sentiment — and label examples directly in the UI while predictions update live.
Outcome: A multi-dimensional classifier for sorting incoming interactions, without an ML engineer in the loop.
Use cases
- Identify contract clauses such as warranty terms inside legal documents
- Flag bullying content across large sets of text messages before it escalates
- Classify customer interactions by request type and sentiment
- Build custom text classifiers for domain-specific research without an NLP engineer
- Prototype a text classification model from task definition to working model in a few hours
- Annotate high-quality text datasets with active learning reducing wasted labeling effort
Setup time & first value
How long it actually takes to get something useful out of Label Sleuth — broken out by persona, not the marketing-page minute.
Plan on a short command-line setup — Anaconda, a Python 3.9 environment, pip install label-sleuth — then minutes to open localhost. The guided tutorial is the fastest route to a first working model; the project frames task definition to working model as a few hours for a domain expert. Python environment troubleshooting is the usual source of delay.
Switching to or from Label Sleuth
How to bring data in from common predecessors and how to get it back out — written for the switcher, not the buyer.
- →From manual spreadsheet tagging: define your label set in Label Sleuth and let active learning order the examples worth reviewing.
- →From a hand-rolled labeling script: move the task into the annotation UI and get automatic background training and live predictions for free.
- →From a dependency on an NLP engineer: domain experts label in the UI themselves instead of handing off a spec.
- ↗To a commercial annotation platform: export your labeled examples and re-create the label set in the hosted tool if you outgrow local operation.
- ↗To a self-built model pipeline: pull the labeled dataset from Label Sleuth and train your own architecture outside the system.
Resources & guides
Tutorials & Learning

Introducing Label Sleuth - an open source for quickly building text classifiers with no AI knowledge
Eish narch

Katsis & Shnarch - Create text classifiers in a few hours using the open-source Label Sleuth system
PyData
YouTube returned 6 videos for “Label Sleuth”, and we withheld 4: 4 did not mention Label Sleuth. Showing the 2 we can prove are about Label Sleuth.
Official links
What are the best Label Sleuth alternatives?
The closest alternatives to Label Sleuth we list are Teachable Machine, LabelStudio and Datasets. Ranked by direct product-type match, not category overlap.
| Alternative | Pricing | Starts at | Last verified |
|---|---|---|---|
| Teachable Machine | Free | Free | — |
| LabelStudio | Freemium | Pricing not published | — |
| Datasets | Free | Free | — |
Alternatives to Label Sleuth
View allTeachable Machine
Free browser tool from Google for training image, sound, and pose classifiers with no code and no account.
LabelStudio
Open-source data labeling and AI evaluation across every data modality, self-hosted.
Tools that pair well with Label Sleuth
Common stack mates teams adopt alongside Label Sleuth, with the specific reason each pairing earns its keep.
Teachable Machine
Free browser tool from Google for training image, sound, and pose classifiers with no code and no account.
LabelStudio
Open-source data labeling and AI evaluation across every data modality, self-hosted.
Datasets
Load, stream, and preprocess training datasets in one line of Python — open source, Arrow-backed, Hub-native
Label Sleuth vs its closest rival
Label Sleuth's closest head-to-head is with Praktika — Praktika and Label Sleuth serve entirely different needs. Praktika is a mobile language tutor for speaking fluency, ideal for intermediate learners wanting AI conversation practice. Label Sleuth is a desktop open-source tool for text annotation and classifier building, perfect for domain experts without coding skills. Choose based on your goal: improve spoken language or label text data. Verdict generated
Head-to-head comparisons
Label Sleuth vs Praktika
Praktika and Label Sleuth serve entirely different needs. Praktika is a mobile language tutor for speaking fluency, ideal for intermediate learners wanting AI conversation practice. Label Sleuth is a desktop open-source tool for text annotation and classifier building, perfect for domain experts without coding skills. Choose based on your goal: improve spoken language or label text data.
GeneratedLabel Sleuth vs Screenplayiq
If you need a data-driven, financial forecast for your feature film script, ScreenplayIQ is your tool – but it's paid and limited to feature-length English screenplays. If you're a domain expert (e.g., legal, healthcare) who needs to build a custom text classifier without coding, Label Sleuth is free and open source, running locally for privacy. They serve entirely different needs and don't compete directly.
GeneratedFrequently asked questions
Categories
Best-of guides
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