AI Data Annotation Services · San Francisco

AI Annotation Services in San Francisco

Synnth delivers production-grade image, video, text, and audio annotation services to AI and machine learning teams across San Francisco — with human-in-the-loop QA, domain-expert annotators, and 48h pilot delivery.

About Us

Trusted by AI teams worldwide

100M+

Items annotated

98.5%

QA accuracy

40+

Languages

2K+

Domain expert annotators

48h

Pilot batch turnaround

AI Data Annotation Services for San Francisco Teams

Synnth provides high-quality, scalable AI annotation services in San Francisco designed to support machine learning and AI initiatives across industries. As AI models grow more complex, accurate and consistent data annotation becomes critical to performance, reliability, and real-world deployment.

Our AI annotation services in San Francisco combine human-in-the-loop expertise, rigorous multi-stage quality workflows, and secure infrastructure to deliver training-ready datasets for computer vision, natural language processing, speech recognition, and multimodal AI systems. Whether you are building proof-of-concept models or scaling enterprise-grade AI, Synnth delivers annotation services tailored to your business needs.

Annotation Services Available in San Francisco

Image Annotation

Precise image labeling for computer vision — bounding boxes, polygon segmentation, keypoints, semantic segmentation, 3D cuboid annotation, and image classification across 40+ object categories.

Bounding boxes Segmentation Keypoints 3D cuboids COCO · VOC · YOLO

Video Annotation

Frame-accurate video labeling — multi-object tracking with persistent IDs, temporal activity segmentation, action recognition, pose tracking, and event and anomaly detection across video clips.

Object tracking Action labels Temporal segmentation MOT · AVA · COCO Video

Text & NLP Annotation

Expert text labeling for NLP and LLM models — named entity recognition, sentiment annotation, intent and slot labeling, relation extraction, coreference resolution, and RLHF preference ranking.

NER Sentiment RLHF Intent labels CoNLL · BRAT · JSONL

Audio & Speech Annotation

Speech transcription, speaker diarization, sound event detection, phoneme alignment, emotion tagging, and voice activity detection — by native-speaker annotators across 40+ languages.

Transcription Diarization Sound events Phonemes TextGrid · ELAN · JSON

Why San Francisco AI Teams Choose Synnth

What San Francisco AI teams consistently tell us separates Synnth from generic labeling platforms and offshore annotation pipelines.

Human-in-the-loop
QA

Every annotation reviewed by expert humans — not just automated checks. We don’t trust quality to algorithms alone, because edge cases require judgment, not pattern matching.

99.2% QA pass rate

Domain-expert
annotators

Legal text annotated by legal professionals. Medical data by clinicians. Financial records by finance specialists. Domain expertise is the difference between useful labels and noise.

200+ specialists

Native-speaker
multilingual

Every language annotated by native speakers — not translators working in a second language. For 40+ languages, including the regional variety and dialect coverage your San Francisco-focused product may need.

40+ languages

Enterprise
security

All data encrypted at rest and in transit. GDPR compliant, HIPAA-ready for healthcare. NDAs on every engagement. Proprietary data never leaves our controlled, access-audited environments.

Fast pilot
SLA

Validate annotation quality before committing to scale. Pilot batches in 48–72 hours — with the same QA standards and annotator pool used for full production runs.

48h pilot delivery

Dedicated project
management

Every project gets a named project manager — your single point of contact for scope changes, quality questions, and delivery scheduling. No ticket queues, no account managers who don’t know your data.

How the Annotation Process Works

The same four-stage pipeline applies to every San Francisco client — with dedicated project management and full QA transparency at every step.

Scope &
specification

Share your use case, data modality, label taxonomy, language targets, and quality requirements. We produce a detailed specification — annotation schema, edge-case decision rules, and QA rubrics — within one business day.

Match domain-expert annotators

We assign annotators matched to your domain — not just your data type. Legal text goes to legal professionals; medical data to clinicians; technical audio to domain engineers. Annotators are calibrated on your task before production begins.

Annotate with multi-stage QA

Every batch passes automated consistency validation, inter-annotator agreement (IAA) measurement on calibration samples, and senior reviewer sign-off. Batches below QA threshold are re-annotated before delivery.

Deliver with full QA report

Receive your dataset in your preferred format — COCO JSON, CoNLL, TextGrid, MOT CSV, or custom schema — alongside a full QA report with per-class accuracy, IAA scores, rejection rates, and revision log. Free revisions within scope.

Industries we serve in San Francisco

San Francisco’s AI ecosystem spans finance, health, media, legal, retail, and enterprise software. Our annotators are matched to your industry’s terminology and standards.

Financial Services

NLP annotation for risk models, fraud detection, compliance AI, earnings call sentiment, and financial entity recognition — matched to Wall Street’s domain vocabulary.

Healthcare & Life Sciences

HIPAA-ready medical image annotation, clinical note NLP, radiology labeling, and EHR classification — by annotators with clinical training.

Legal & Professional Services

Contract NLP, legal entity extraction, clause classification, and document annotation by legal professionals with jurisdiction-specific expertise.

Media & Advertising Tech

Content classification, brand safety labeling, sentiment annotation, and video action labeling for San Francisco’s media and adtech companies.

Retail & E-Commerce

Product image annotation, visual search training data, attribute tagging, and review sentiment labeling for retail AI and recommendation systems.

Enterprise & SaaS AI

Document understanding datasets, meeting transcription annotation, workflow automation training data, and RLHF preference data for enterprise AI features.

FAQ

Questions about AI data annotation in San Francisco

Common questions from San Francisco AI teams considering Synnth for their data annotation needs.

💡 Can’t find your answer here? Talk to our team — we typically respond within one business day.

Does Synnth provide annotation services in San Francisco?

Yes. Synnth provides AI data annotation services to machine learning and AI teams across San Francisco and the wider San Francisco area. Services include image annotation, video labeling, text and NLP annotation, and audio and speech transcription — all delivered remotely with the same SLAs, QA standards, and dedicated project management as any global enterprise client. There is no location-based delay or surcharge for San Francisco teams.

What types of annotation services are available in San Francisco?

Synnth offers four primary annotation service categories to San Francisco teams: Image annotation — bounding boxes, polygon segmentation, keypoints, semantic and instance segmentation, 3D cuboid annotation, image classification, OCR and text detection, and medical image labeling (HIPAA-ready). Video annotation — bounding box tracking, temporal activity segmentation, action and activity recognition labeling, pose and keypoint tracking in video, event and anomaly detection, and video semantic segmentation. Text & NLP annotation — named entity recognition, sentiment and emotion labeling, intent and slot annotation, relation extraction, coreference resolution, RLHF preference ranking, instruction tuning data, and question-answer pair creation. Audio & speech annotation — speech transcription (verbatim and normalized), speaker diarization, sound event detection, phoneme and word alignment, emotion tagging, voice activity detection, and audio quality assessment.

How quickly can Synnth start and deliver a project for a San Francisco AI team?

After an initial scoping discussion, we can begin a pilot batch within 24–48 hours. Pilot batches are delivered within 48–72 hours at full production QA standards. There is no location-based delay for San Francisco clients. For qualifying projects, Synnth offers a free pilot batch so teams can validate annotation quality before committing to full-scale production volumes.

How does Synnth ensure annotation quality?

Synnth applies a multi-stage QA pipeline to every annotation project: (1) Automated validation — geometry checks for image and video tasks, format validation for text, acoustic quality screening for audio; (2) Inter-annotator agreement (IAA) — measured on calibration samples using Cohen’s kappa (two annotators) or Fleiss’ kappa (three or more), targeting above 0.80 on standard tasks; (3) Senior reviewer sign-off — every batch reviewed and approved by a senior annotator before delivery. Synnth maintains a 98.5% average QA accuracy across delivered projects, and every delivery includes a full QA report with per-class accuracy, IAA scores, and revision logs.

Can Synnth handle HIPAA-compliant annotation for San Francisco healthcare AI?

Yes. Healthcare annotation projects — medical image labeling, clinical note NLP, EHR classification — are handled under HIPAA-ready protocols: access-controlled annotation environments, Business Associate Agreements (BAAs) where required, annotators with relevant clinical training, full audit trails, and strict NDA coverage. This is available to San Francisco hospital systems, healthtech startups, pharma companies, and clinical research institutions.

What languages does Synnth support for annotation in San Francisco?

Synnth supports annotation in 40+ languages with native-speaker annotators for each — covering all major world languages as well as regional and low-resource languages. For San Francisco-focused AI products, this includes Spanish, Mandarin, Cantonese, Hindi, Bengali, Arabic, Russian, Korean, Polish, Haitian Creole, Tagalog, and many more. All annotation is performed by native speakers — not translators — to ensure linguistic accuracy and cultural nuance.

How is pricing structured for San Francisco annotation projects?

Pricing is based on annotation task complexity, data volume, language requirements, turnaround time, and domain expertise required — not on client location. There is no location-specific pricing for San Francisco teams. Synnth accepts pilot batches from 1,000 items with no setup fee, and free revisions are included within scope. Contact us for a free, no-commitment estimate.

What output formats are annotations delivered in?

Annotations are delivered in your preferred format at no additional cost:

Image: COCO JSON, Pascal VOC XML, YOLO TXT, LabelMe JSON, TFRecord, Cityscapes, KITTI, custom schema
Video: COCO Video JSON, MOT CSV, AVA JSON, Kinetics-style JSON, CVAT XML, Waymo TFRecord, custom schema
Text: JSON, JSONL, CoNLL-2003, BRAT standoff, Label Studio JSON, Prodigy JSONL, Hugging Face Datasets format, SQuAD JSON, CSV
Audio: TextGrid (Praat), ELAN EAF, WebVTT, SRT, JSON, CSV, CTM, custom schema

How is proprietary data kept secure during annotation?

All data is transferred through TLS-encrypted channels (TLS 1.3) and stored at rest with AES-256 encryption. Annotation work is performed only within access-controlled, audited environments — annotators access data through Synnth’s secure platform and cannot download or export raw files. NDAs are signed on every engagement. For regulated industries, Synnth operates under data processing agreements with custom access controls. Proprietary data is never used for any purpose beyond your project.

San Francisco · AI Data Annotation

Start your AI data annotation project with Synnth — serving San Francisco teams

Tell us your use case, modality, languages, and volume. Our team responds within one business day with a scoping plan and no-obligation quote — available to San Francisco AI teams at the same SLAs as any global enterprise client.