98%+ annotation accuracy · All data types

Data Annotation Services

Your ML models need training data labeled accurately at scale, but your engineering team can’t keep up. Acelerar’s trained annotators handle image, text, audio, and video annotation with 98%+ accuracy and multi-tier QA, so your models train on reliable data from day one.

Data annotation interface showing bounding boxes and polygon annotations on images alongside text classification labels
500+
Teams Deployed
99.5%
Accuracy SLA
70%
Avg Cost Savings
7-Day
Team Deployment
4.9 out of 5·from 120+ verified reviews
Clutch (4.9)Google (4.8)GoodFirms (5)

What are data annotation services?

Data annotation is the process of labeling raw data - images, text, audio, and video - with structured tags that machine learning models use for training. Without accurately annotated data, supervised learning models cannot learn to classify, detect, or predict. Annotation types include bounding boxes for object detection, polygon segmentation for pixel-level precision, named entity recognition for text, sentiment labeling, audio transcription with speaker diarization, and video frame-by-frame tracking. The challenge is not just labeling data, but labeling it consistently at scale with quality controls that prevent noisy training sets from degrading model performance.

The data management outsourcing market

Data management outsourcing is growing as businesses deal with increasing data volumes.

$245B+
India IT-BPM industry revenue
NASSCOM, 2024
5.8M+
IT professionals in India
NASSCOM, 2024
15-30%
Average cost savings from outsourcing
IAOP, 2023

Every annotation type your ML pipeline needs

Image & video annotation

Bounding boxes, polygon segmentation, polyline annotation, keypoint detection, and semantic segmentation for computer vision models. We handle everything from simple 2D object detection labels to complex 3D point cloud annotation for autonomous driving datasets. Our annotators are trained on specific object taxonomies and follow your labeling guidelines with inter-annotator agreement rates above 95%.

See data labeling services
Image annotation workspace showing bounding boxes around vehicles and pedestrians with classification labels and confidence scores

Text & NLP annotation

Named entity recognition, sentiment analysis, intent classification, part-of-speech tagging, text summarization, and relation extraction. We annotate in 15+ languages for multilingual NLP models. Our text annotation teams are domain-trained for medical, legal, financial, and technical content where terminology matters for accurate labeling.

See data management services
Text annotation interface showing named entities highlighted in different colors with entity type labels and relationship arrows

Audio & speech annotation

Audio transcription, speaker diarization, emotion detection, sound event classification, and phonetic annotation. We process conversational AI training data, voice assistant datasets, and call center recordings with timestamp-level precision. Multi-speaker scenarios and noisy audio environments are handled by annotators trained in acoustic labeling protocols.

See data labeling services
Audio annotation timeline showing speech segments labeled by speaker with emotion tags and transcription text overlay

The real cost of in-house data annotation

A full-time data annotator in the US costs $38,000 to $48,000/year with benefits. With Acelerar, you get trained annotation teams for a fraction, and scale with your ML pipeline.

In-House Data Annotator (US)

$42K/yr

per year / per person

Salary · Benefits · Annotation tools · QA reviews

Acelerar Data Annotation

$13K/yr

per year / per person

Guideline-calibrated · Multi-format · 95%+ agreement

Why ML teams outsource annotation to Acelerar

98%+ Annotation Accuracy

Multi-tier QA process: annotator self-review, peer review on 20% of samples, and senior reviewer spot-checks. Inter-annotator agreement measured and reported for every batch.

Trained Domain Annotators

Our annotators are trained on your specific taxonomy, labeling guidelines, and edge case protocols before the first label is placed. No generic crowdsourcing - dedicated teams that learn your domain.

Scale to Millions of Labels

From 1,000 images to 1,000,000+. Our team capacity scales within days, not weeks. Maintain consistent quality at 10x volume because trained annotators follow the same guidelines at every scale.

All Annotation Types Covered

Bounding box, polygon, polyline, keypoint, semantic segmentation, NER, sentiment, intent, audio transcription, speaker diarization - one vendor for every annotation need in your pipeline.

70% Cost Savings vs. US Annotators

US-based annotation teams cost $25-$40/hour per annotator. Acelerar delivers the same quality at 70% less, freeing budget for more training data and faster model iteration cycles.

Platform Agnostic

We work within your preferred annotation tool - Labelbox, CVAT, Prodigy, Label Studio, V7, Scale, or custom platforms. No tool migration required. We adapt to your workflow, not the other way around.

From raw data to ML-ready annotations in 5 steps

1

Define

We review your annotation guidelines, taxonomy, and edge cases. Unclear instructions are clarified before labeling begins to prevent rework.

2

Calibrate

Annotators complete a pilot batch (100-500 samples). You review, provide feedback, and we calibrate until the output matches your expectations.

3

Annotate

Full-scale annotation begins with trained, dedicated annotators following your guidelines. Daily output tracked and quality metrics reported.

4

Review

Multi-tier QA: self-review, peer review on 20% of samples, and senior reviewer validation. Inter-annotator agreement scores calculated per batch.

5

Deliver

Annotated data exported in your required format (COCO, Pascal VOC, YOLO, custom JSON) with quality report and annotation statistics.

ML pipeline bottlenecked by annotation?

Send us your annotation guidelines and a sample dataset. We’ll return a pilot batch within 5 days so you can evaluate quality before committing.

Start a Pilot Project

We work with your data platforms

Our teams are trained on the platforms you already use.

What our data management clients say

The Acelerar team is a self-sustaining machine. They’ve become an extension of our own team.

We needed reliable, fast data entry at scale. Acelerar delivered consistent quality from day one, no ramp-up time needed.

Acelerar handled our entire catalog migration (50,000+ SKUs) without a single missed deadline.

Where data management outsourcing is heading

Data volumes are exploding, and outsourced data management teams are evolving with AI capabilities.

2025
$854.6B
Global BPO market size
Grand View Research, 2024
2030
$350B
Projected Indian IT-BPM industry revenue
NASSCOM, 2024
2030
59%
Of workers will need upskilling by 2030
World Economic Forum, 2023
ISO 27001 Certified
ISO 9001:2015
NDA for Every Team Member
Encrypted Data Transfer

Data Annotation Services FAQs

Data annotation services involve labeling raw data (images, text, audio, video) with structured tags that machine learning models need for training. This includes bounding boxes for object detection, text classification for NLP, audio transcription for speech models, and many other annotation types depending on your model architecture.
We provide image annotation (bounding box, polygon, semantic segmentation, keypoint, polyline), text annotation (NER, sentiment, intent, POS tagging, relation extraction), audio annotation (transcription, speaker diarization, emotion detection, sound classification), and video annotation (object tracking, frame-by-frame labeling, activity recognition).
Pricing varies by annotation type and complexity. Simple image bounding boxes start at $0.02-$0.05 per annotation. Polygon segmentation ranges from $0.05-$0.15 per object. Text NER averages $0.01-$0.03 per entity. Audio transcription is $0.50-$1.50 per minute. Volume discounts apply for projects over 50,000 annotations.
The terms are often used interchangeably, but technically data annotation refers to adding detailed metadata and attributes (like bounding box coordinates with class labels), while data labeling is the broader act of assigning any kind of tag to data. In practice, both describe the same work: preparing human-labeled training data for ML models.
We use a multi-tier QA pipeline: annotator self-review, peer review on 20% of samples, senior reviewer validation, and inter-annotator agreement (IAA) scoring. Consensus labeling is used for ambiguous cases. We track and report quality metrics per batch, and annotators who fall below accuracy thresholds receive additional training.
We work with Labelbox, CVAT, Label Studio, Prodigy, V7 (Darwin), SuperAnnotate, Amazon SageMaker Ground Truth, Scale AI, and custom annotation platforms. We adapt to your existing toolchain rather than requiring tool migration. If you use a proprietary tool, we can train on it within days.
Yes. We annotate text in 15+ languages including English, Spanish, French, German, Portuguese, Chinese (Simplified and Traditional), Japanese, Korean, Arabic, Hindi, and more. Our multilingual annotators are native speakers trained in NLP annotation protocols for their specific language.
Pilot batches (100-500 samples) are delivered in 3-5 business days. Standard projects (5,000-50,000 annotations) take 2-4 weeks. Large-scale projects (100,000+ annotations) are delivered in weekly batches with ongoing quality reporting. Timelines depend on annotation complexity and review cycles.
Yes. Bounding box annotation is our highest-volume image annotation service, used for object detection model training. Polygon annotation provides pixel-level precision for segmentation models. We also offer 3D cuboid annotation, keypoint annotation for pose estimation, and polyline annotation for lane detection and boundary marking.
We establish edge case protocols during the calibration phase: your team defines how to handle ambiguous samples, and we document these decisions in a living annotation guide. During production, ambiguous samples are flagged for senior review rather than guessed at. We escalate recurring edge cases to you for guideline updates.

Need high-quality training data for your ML models?

Get a pilot annotation batch and quality report within 5 business days.

No commitment required. We respond within 24 hours.