Two bilingual annotators in a Mexico City office comparing notes on a printed labeling guideline, laptops open, afternoon light

/Nearshore · Data Annotation

Nearshore data annotation, calibrated on your hours.

Nearshore data annotation puts the people who label your training data in Mexico or Colombia, in time zones that share most of the US working day. It fits best when the guidelines are still moving, when the data is in Spanish or mixes Spanish and English, and when your ML team wants to settle edge cases on a call instead of in a ticket. This guide covers which tasks suit the model, how a project runs from pilot to production, how to keep data safe and when offshore is the better choice. For the service itself, see our data annotation outsourcing page.

What nearshore data annotation is

A nearshore annotation team works from a neighboring country, during your business day, inside the labeling platform you already use. For US companies the two strongest locations are Mexico and Colombia, and the clock is a big part of why.

Mexico’s time-zone law, published in October 2022, ended daylight saving time for most of the country. Mexico City, Guadalajara and Monterrey stay on UTC-6 all year, which matches US Central in winter and Mountain in summer. Colombia stays on UTC-5 all year, matching US Eastern in winter and Central in summer.

That overlap changes how annotation work moves. A question about an ambiguous image or an odd utterance goes to your ML engineer in the morning and the answer is in the guideline by lunch, not the next day.

Sources: Mexico, Ley de los Husos Horarios (Cámara de Diputados) Colombia legal time, Instituto Nacional de Metrología

Where nearshore teams add the most

Any annotation task can run nearshore, but some get much more out of shared hours and native Spanish. These are the strongest fits:

  • Spanish and bilingual text: intent and entity labeling, sentiment, and classification of customer messages written in Latin American Spanish.
  • Code-switching: chats, calls and social posts that mix Spanish and English in the same sentence, which monolingual annotators tend to mislabel.
  • Speech and transcription in Spanish, with regional vocabulary, slang and accents from Mexico, Colombia and the wider region.
  • LLM evaluation and preference ranking, where annotators judge whether an answer is correct, helpful and natural in Spanish or English.
  • Search and recommendation relevance for Spanish-speaking markets, where local context decides what a good result is.
  • Early-stage projects of any kind, where the label set and guidelines are still changing week to week.

Why Spanish-language nuance matters

Spanish is not one dataset. The same word can be neutral in one country and rude in another, and a model trained on labels from someone who doesn’t know the difference learns the wrong thing.

Annotators in Mexico and Colombia read Latin American Spanish as native speakers and work in English with your team. They catch sarcasm, regional slang and the switch from Spanish to English mid-sentence that a translated guideline never mentions. When they find a pattern your guideline doesn’t cover, they can explain it to your team the same day, in English.

How a nearshore annotation project runs

Good annotation is a loop, not a handoff. Here’s the sequence we use, with the nearshore advantage at each step being speed of iteration.

  • Guidelines Your team writes the label definitions with examples of correct, incorrect and borderline cases. The guidelines are yours.
  • Pilot batch A small set is labeled first, and every disagreement or question is logged.
  • Calibration Annotators, a lead reviewer and your ML engineer meet live to walk through the hard cases and update the guideline. With shared hours, this can happen several times in a week.
  • Gold checks Items with an answer your team already agreed on are mixed into the queue without being flagged, so you can see who is drifting and on which labels.
  • Agreement checks Some items go to two or more annotators. If they often disagree on a label, the guideline is usually unclear, and you fix the guideline before blaming the people.
  • Production Volume grows only after the pilot matches your expectations, with a reviewer sampling the work before it reaches your training set.

Security on your platform

Your data should never leave your control. The safest setup has annotators working inside your own annotation platform or a vendor workspace you administer, not on copies of your files. Put these rules in writing before anyone logs in:

  • Named accounts for every annotator, with single sign-on or multi-factor authentication. No shared logins.
  • Access limited to the projects and data each person needs, and removed the day someone leaves the team.
  • No downloads, screenshots or copying of data out of the platform, enforced by settings where your tools allow it.
  • Personal information removed or masked before data reaches annotators whenever the task doesn’t need it.
  • Managed devices and a clean workspace at the partner center, with the rules written into the contract.

Wellbeing for moderation and sensitive content

Some annotation work means looking at violent, sexual or hateful material, whether for content moderation or for training a safety classifier. People who do that work need protection built into the project, not offered as an extra.

We agree these measures with the partner center before launch: annotators know what the queue contains before they accept it, exposure time per shift is limited, people rotate between sensitive and ordinary queues, tools blur or gray out images by default where the task allows, and confidential counseling is available. Anyone can step off a sensitive queue without penalty.

Nearshore compared with onshore and offshore

Many ML teams use more than one model for different parts of the data pipeline. Here’s how the three compare for annotation work.

Onshore (US)Nearshore (Mexico, Colombia)Offshore (Philippines, India, Egypt)
Relative costHighestMiddleLowest
Shared hours with your ML teamFullMost or all of the dayLimited unless the team works night shifts
Guideline changesSame daySame day, often on a callNext shift, through written updates
Spanish and code-switched dataSmall pool, high costNativePoor fit
Best forExpert or cleared reviewersBilingual data and fast-changing guidelinesLarge, stable, well-specified queues

When offshore is the better fit

Nearshore isn’t the answer for every dataset. Offshore usually wins when the task is stable, the guideline is settled and the volume is large: bounding boxes on hundreds of thousands of images, frame-by-frame video tracking, English transcription or moderation queues that run around the clock.

If nobody on your side needs to answer questions while the work is being done, the shared hours you pay for in nearshore matter less, and a team that works while you sleep gives you labeled data every morning.

Many teams split the work: nearshore to design and calibrate the task, and to handle Spanish data, then offshore to run the stable queue at volume.

What to ask a nearshore annotation provider

Shared hours are the starting point. These questions show how a provider will actually run your data.

  • Which country and city would the team work from, and which hours exactly?
  • Will annotators work inside our platform, and what stops data leaving it?
  • How are gold items and agreement checks used, and will we see the raw results?
  • Who calibrates with our ML team, and how often?
  • How are Spanish speakers assessed, and from which countries are they drawn?
  • What wellbeing measures apply to sensitive content, and can annotators opt out?

Mexico, Colombia or both

OTRO runs annotation teams in Mexico and Colombia through partner centers we select and manage, under one contract and one set of reports. Two countries give you two hiring markets with nearly the same hours and a wider range of Spanish. For scope, process and how a project starts, see the data annotation outsourcing page.

Frequently asked questions

What is nearshore data annotation?

It’s labeling training data with a team in a nearby country that works during your business day. For US companies that usually means Mexico or Colombia. The team works inside your annotation platform on your guidelines, and the shared hours let your ML team calibrate with annotators live instead of through overnight tickets.

What is the difference between nearshore and offshore data annotation?

Time zone, language and cost. A nearshore team in Mexico or Colombia shares your day and works natively in Spanish, so it suits bilingual data and guidelines that are still changing. An offshore team in the Philippines, India or Egypt usually costs less and works while you sleep, so it suits large, stable queues with written guidelines. Many teams use both.

How do you measure annotation quality?

With checks you can see. Gold items with known answers are mixed into the queue, some items go to more than one annotator to measure how often they agree, and a reviewer samples finished work. The results go to your team as raw data, so you decide whether the labels are good enough to train on.

Does our data leave our platform?

It shouldn’t. Annotators work inside the platform you control, with named accounts, limited access and downloads turned off where your tools allow it. Personal information should be removed or masked before annotators see it whenever the task doesn’t need it. Put these rules in the contract before work starts.

How much does nearshore data annotation cost?

It usually costs less than an onshore team and more than an offshore one. The price depends on task type, volume, language, how stable the guidelines are and how much review you want, so we quote per scope. Compare total cost, including rework from labels that missed the guideline.

Plan your annotation delivery model

Tell us your data types, languages, volume and platform. We’ll come back with a written plan: where each task should run, how the pilot will be calibrated and how quality will be checked.

Get a delivery plan