Perl

Hire the Top 3% of Freelance Perl Developers

Toptal is a marketplace for top Perl developers, engineers, programmers, coders, architects, and consultants. Top companies and start-ups choose Toptal Perl freelancers for their mission-critical software projects.

No-Risk Trial, Pay Only If Satisfied.

Clients Rate Toptal Perl Developers4.2 / 5.0on average across 27 reviews as of Sep 24, 2020

Hire Freelance Perl Developers and Engineers

Sam Varshavchik

Freelance Perl Developer

United StatesToptal Member Since September 16, 2012

Sam is a senior freelance developer and architect with over 20 years of experience developing in the financial industry.

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Andrii Kostenko

Freelance Perl Developer

FinlandToptal Member Since May 22, 2013

Andrii is an accomplished software engineer experienced in creating large-scale, complex applications. He has worked both as a back-end and front-end engineer. He excels at planning and implementing intricate solutions to technical problems, including determining which technologies should be used.

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Jordan Ambra

Freelance Perl Developer

United StatesToptal Member Since June 6, 2013

Jordan is a top-notch architect, developer, sysadmin, and entrepreneur with the passion and experience to help businesses solve complex problems. He is an expert full-stack developer, bringing projects from concept to completion, with a proven track record of delivering powerful, stable, and comprehensive solutions.

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Tom Stanik

Freelance Perl Developer

United StatesToptal Member Since November 8, 2012

Tom is a seasoned electrical/computer engineer with 15+ years of industrial engineering and coding experience, beginning with work at AT&T/Bell. He is a dedicated, top-notch problem solver with proven ability to get the job done.

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Genadijus Paleckis

Freelance Perl Developer

United KingdomToptal Member Since December 8, 2011

Genadijus has over 15 years of experience as a developer. He can execute programming tasks using a range of programming languages including (but not limited to) JavaScript, PHP, C, and Perl. For the past few years, he's been focusing mainly on Angular and test-driven development.

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Chris Remshaw

Freelance Perl Developer

United StatesToptal Member Since September 20, 2013

Chris is a hands-on architect and developer with many years of experience with companies large and small. With a proven record of customer satisfaction, efficiency, and solution longevity, he is experienced with a variety of languages and tools and is comfortable solo, as a team member, or as a group lead/mentor.

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Flavio de Sousa

Freelance Perl Developer

GermanyToptal Member Since June 13, 2012

Flavio is a top architect/programmer with a long track record of successfully delivering projects for companies ranging from Big Four consulting firms, large telecoms, and government agencies to small team startups. He's eager to design and deliver efficient application architectures.

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Ken Whaley

Freelance Perl Developer

FinlandToptal Member Since September 6, 2012

Ken is a top architect, engineer, and developer with over 30 years of experience in the field. He has a proven ability to understand, optimize, enhance, and create from scratch significant software tools and workflows with large user bases that greatly magnify productivity for large groups of engineers. Ken is eager to take on new challenges and has done so with teams of all sizes and compositions.

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A Hiring Guide

Guide to Hiring a Great Perl Developer

Perl, the tried and true predecessor of modern day dynamic languages, still retains its title as one of the best text processing languages out there and remains the chosen language of many corporate applications. To help you find developers that truly understand this once revolutionary language, follow this hiring guide through the topics and questions that Perl experts should know well.

Read Hiring Guide
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Tripcents wouldn't exist without Toptal. Toptal Projects enabled us to rapidly develop our foundation with a product manager, lead developer, and senior designer. In just over 60 days we went from concept to Alpha. The speed, knowledge, expertise, and flexibility is second to none. The Toptal team were as part of tripcents as any in-house team member of tripcents. They contributed and took ownership of the development just like everyone else. We will continue to use Toptal. As a start up, they are our secret weapon.

Brantley Pace, CEO & Co-Founder

Tripcents

In addition to sharp technical skills, Faruk had a great attitude and is a really exceptional communicator. He always let us know where he was with his work, thoroughly and reliably. That's not always the case, and it made working remotely considerably easier. He was an easy integration into the team.

Leif Abraham, Co-Founder

AND CO Ventures Inc

I am more than pleased with our experience with Toptal. The professional I got to work with was on the phone with me within a couple of hours. I knew after discussing my project with him that he was the candidate I wanted. I hired him immediately and he wasted no time in getting to my project, even going the extra mile by adding some great design elements that enhanced our overall look.

Paul Fenley, Director

K Dunn & Associates

The developers I was paired with were incredible -- smart, driven, and responsive. It used to be hard to find quality engineers and consultants. Now it isn't.

Ryan Rockefeller, CEO

Radeeus

Toptal understood our project needs immediately. We were matched with an exceptional freelancer from Argentina who, from Day 1, immersed himself in our industry, blended seamlessly with our team, understood our vision, and produced top-notch results. Toptal makes connecting with superior developers and programmers very easy.

Jason Kulik, Co-Founder

ProHatch

As a small company with limited resources we can't afford to make expensive mistakes. Toptal provided us with an experienced programmer who was able to hit the ground running and begin contributing immediately. It has been a great experience and one we'd repeat again in a heartbeat.

Stuart Pocknee , Principal

Site Specific Software Solutions

We used Toptal to hire a developer with extensive Amazon Web Services experience. We interviewed four candidates, one of which turned out to be a great fit for our requirements. The process was quick and effective.

Abner Guzmán Rivera, CTO and Chief Scientist

Photo Kharma

Sergio was an awesome developer to work with. Top notch, responsive, and got the work done efficiently.

Dennis Baldwin, Chief Technologist and Co-Founder

PriceBlink

Working with Marcin is a joy. He is competent, professional, flexible, and extremely quick to understand what is required and how to implement it.

André Fischer, CTO

POSTIFY

We needed a expert engineer who could start on our project immediately. Simanas exceeded our expectations with his work. Not having to interview and chase down an expert developer was an excellent time-saver and made everyone feel more comfortable with our choice to switch platforms to utilize a more robust language. Toptal made the process easy and convenient. Toptal is now the first place we look for expert-level help.

Derek Minor, Senior VP of Web Development

Networld Media Group

Toptal's developers and architects have been both very professional and easy to work with. The solution they produced was fairly priced and top quality, reducing our time to launch. Thanks again, Toptal.

Jeremy Wessels, CEO

Kognosi

We had a great experience with Toptal. They paired us with the perfect developer for our application and made the process very easy. It was also easy to extend beyond the initial time frame, and we were able to keep the same contractor throughout our project. We definitely recommend Toptal for finding high quality talent quickly and seamlessly.

Ryan Morrissey, CTO

Applied Business Technologies, LLC

I'm incredibly impressed with Toptal. Our developer communicates with me every day, and is a very powerful coder. He's a true professional and his work is just excellent. 5 stars for Toptal.

Pietro Casoar, CEO

Ronin Play Pty Ltd

Working with Toptal has been a great experience. Prior to using them, I had spent quite some time interviewing other freelancers and wasn't finding what I needed. After engaging with Toptal, they matched me up with the perfect developer in a matter of days. The developer I'm working with not only delivers quality code, but he also makes suggestions on things that I hadn't thought of. It's clear to me that Amaury knows what he is doing. Highly recommended!

George Cheng, CEO

Bulavard, Inc.

As a Toptal qualified front-end developer, I also run my own consulting practice. When clients come to me for help filling key roles on their team, Toptal is the only place I feel comfortable recommending. Toptal's entire candidate pool is the best of the best. Toptal is the best value for money I've found in nearly half a decade of professional online work.

Ethan Brooks, CTO

Langlotz Patent & Trademark Works, Inc.

In Higgle's early days, we needed the best-in-class developers, at affordable rates, in a timely fashion. Toptal delivered!

Lara Aldag, CEO

Higgle

Toptal makes finding a candidate extremely easy and gives you peace-of-mind that they have the skills to deliver. I would definitely recommend their services to anyone looking for highly-skilled developers.

Michael Gluckman, Data Manager

Mxit

Toptal’s ability to rapidly match our project with the best developers was just superb. The developers have become part of our team, and I’m amazed at the level of professional commitment each of them has demonstrated. For those looking to work remotely with the best engineers, look no further than Toptal.

Laurent Alis, Founder

Livepress

Toptal makes finding qualified engineers a breeze. We needed an experienced ASP.NET MVC architect to guide the development of our start-up app, and Toptal had three great candidates for us in less than a week. After making our selection, the engineer was online immediately and hit the ground running. It was so much faster and easier than having to discover and vet candidates ourselves.

Jeff Kelly, Co-Founder

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We needed some short-term work in Scala, and Toptal found us a great developer within 24 hours. This simply would not have been possible via any other platform.

Franco Arda, Co-Founder

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How to Hire Perl Developers through Toptal

1

Talk to One of Our Industry Experts

A Toptal director of engineering will work with you to understand your goals, technical needs, and team dynamics.
2

Work With Hand-Selected Talent

Within days, we'll introduce you to the right Perl developer for your project. Average time to match is under 24 hours.
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The Right Fit, Guaranteed

Work with your new Perl developer for a trial period (pay only if satisfied), ensuring they're the right fit before starting the engagement.

FAQs

  • How are Toptal Perl developers different?

    At Toptal, we thoroughly screen our Perl developers to ensure we only match you with talent of the highest caliber. Of the more than 100,000 people who apply to join the Toptal network each year, fewer than 3% make the cut. You'll work with engineering experts (never generalized recruiters or HR reps) to understand your goals, technical needs, and team dynamics. The end result: expert vetted talent from our network, custom matched to fit your business needs. Start now.

  • Can I hire Perl developers in less than 48 hours through Toptal?

    Depending on availability and how fast you can progress, you could start working with a Perl developer within 48 hours of signing up. Start now.

  • What is the no-risk trial period for Toptal Perl developers?

    We make sure that each engagement between you and your Perl developer begins with a trial period of up to two weeks. This means that you have time to confirm the engagement will be successful. If you're completely satisfied with the results, we'll bill you for the time and continue the engagement for as long as you'd like. If you're not completely satisfied, you won't be billed. From there, we can either part ways, or we can provide you with another expert who may be a better fit and with whom we will begin a second, no-risk trial. Start now.

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Perl

How to Hire a Great Perl Developer

While Perl may not be as popular as it had once been, many of the dynamic languages and web technologies that power the web today—such as JavaScript, PHP, Python, and Ruby—were all influenced by Perl. You can still see the design decisions that were made in Perl 30 years ago present in those languages today.

First released in the late 1980s by creator Larry Wall, Perl was in the right place at the right time and quickly became a major player in the development of the internet. As one of the first dynamically typed languages, it gave developers the tools to quickly do things that couldn’t be done before. No longer would they need to pre-allocate memory or keep track of which data type a variable stored.

Perl still remains one of the best programming languages for text processing with regular expressions, which makes it very easy to use for processing file input and output. Perl is also commonly used in system administration, web services, database design using MySQL and Oracle DBA, open-source and shell scripting projects. Many developers choose Perl instead of ASP.NET because it has a lot of libraries, it’s open-sourced and is powerful. Also, Perl fans use it instead of Bash and Unix Shell, since you can write both short programs or huge distributed applications there, while in BASH or other Unix shells writing huge applications is rather difficult.

If you are looking to hire Perl developers, it’s probably because you have a legacy Perl application or you’re looking to take advantage of the power of its regular expressions engine. This hiring guide covers the basic, key aspects that every Perl programmer should know inside and out.

References

As mentioned before, Perl programming brought on a major shift in programming and heralded an evolution from statically typed to dynamically typed languages. One of the other shifts it ushered in was the way references are used. The concept of pointers, common in predecessor languages like C and C++, were confusing to many developers, so Perl did away with pointers and instead introduced references, which simplified memory management for the developer.

References are used frequently and extensively in Perl code. They’re very important for a Perl web developer to understand, as the syntax of element access changes depending on whether you have a reference or direct access.

Q: In Perl, how do you initialize the following?

  • an array

  • an array reference

  • A hash

  • A hash reference

Furthermore, how would you change an array to an array reference, a hash to a hash reference, and vice versa? How do you access elements from within these variables?

A: The use of hash and array references is a pretty basic concept for any experienced Perl developer, but it may syntactically trip up some newer Perl developers or developers who never really grasped the underlying basics.

Initializing an Array:

my @arr = (0, 1, 2);

An array is initialized with an @ symbol prefixed to the variable name, which denotes the variable type as an array; its elements are placed in parentheses.

Initializing an Array Reference:

my $arr_ref = [0, 1, 2];

With an array reference, you use the $ symbol, which denotes ‘scalar’, and the elements are placed in square brackets. The reference isn’t specified as an array, just as a scalar, so you have to be careful to handle the variable type appropriately.

With hashes, the syntax is similar.

Initializing a Hash:

my %hash = (0 => 'First', 1 => 'Second', 2 => 'Third');

Just as with an array, the elements of a hash are defined with parentheses, but since the variable is a hash, it’s prefixed with a %.

Initializing an Array Reference:

my $hash_ref = {0 => 'First', 1 => 'Second', 2 => 'Third'};

Like an array reference, a hash reference variable is prefixed with a $, but the elements are placed in curly braces.

Referencing a Hash or an Array

Referencing an array or hash is pretty straightforward. In Perl, a backslash in front of a variable will return the reference to it. You should expect something like the following:

my $arr_ref = \@arr;

my $hash_ref = \%hash;

Dereferencing

Dereferencing a referenced variable is as easy as reassigning it with the appropriate variable identifier. For example, here’s how you would dereference arrays and hashes:

my @arr = @$arr_ref;

my %hash = %$hash_ref;

Accessing Elements

The differences between accessing elements of these variable types and their reference versions is another area where amateur developers may get tripped up.

# to access an element of an array
my $element = $arr[0];

Notice that for an array you are not using the @ prefix but rather the $ to denote a scalar, which is the type returned when accessing any element of an array. Accessing the elements of an array reference, a hash, and a hash reference follows a similar syntax:

# to access an element of an array reference
my $element = ${$array_ref}[0];


# to access an element of a hash
my $element = $hash{0};


# to access an element of a hash reference
my $element = $hash_ref->{0};

Special Variables

One of the things unique to Perl is the number of special variables it provides. While this can make Perl code very concise, it also makes it rather cryptic to new developers. While only those with expert Perl knowledge will know most (or all) of the special variables, there are some key ones that every Perl developer, regardless of skill level, should be familiar with.

Q: Using $_: Verbally explain the functionality of the following example code snippet:

my @new = map { $_ + 1 } @values;

A: The map function will loop through each element in the @values array and $_ will be set to the element of each iteration. This is equivalent to the following more common and verbose code:

my @new = ();
foreach (@values) {
	push(@new, $_ + 1);
}

or

my @new = ();
foreach my $value (@values) {
	push(@new, $value + 1);
}

Q: Using @_: Within the following routine, explain the value of @_:

sub my_subroutine {}

A: @_ will be set to any parameters that are passed into the subroutine.

So, for example, if the subroutine is called as follows:

my_subroutine(1, 'string', 2);

…then @_ will be an array containing the elements (1, 'string', 2).

Regular Expressions

Perl provides a powerful and easy way to work with regular expressions. Even if developers are not doing text processing, they will no doubt come across situations in Perl where regular expressions are the best fit for the job.

Q: Explain what the following code does, in detail:

$str =~ s/-//g;

A: It removes all hyphens (- characters) from the string.

Here we have the variable $str which contains a string.

The =~ is the Perl operator for performing a regular expression.

The s on the left side indicates that we are going to perform a substitution.

The slashes after the s respectively demarcate the regular expression pattern to match and its replacement. After the slashes come any optional modifiers. Let’s take it apart piece by piece:

In this example, - is matching all hyphens.

The second set of slashes, //, is empty, so the matching hyphens in the first part are being replaced by nothing (i.e., deleted.)

The g is a modifier telling the regular expression engine to execute this globally on the string; without the g modifier, only the first hyphen would be removed.

Q: Write a script that takes a list of file names as command-line arguments. Its processing will take these log files of errors and count how many errors occurred on specific days.

For any line that starts with a timestamp in the format of YYYY-MM-DD, increment the counter for that day and print a summary, in ascending date order, like the following:

Example output:

2016-06-01: 3
2016-06-02: 4
2016-06-04: 1

Days that don’t appear in the log file do not need to appear in the output.

A: One concise answer would look like the following:

my %counts = ();
while (<>) {
	if (/^(\d{4}-\d{2}-\d{2})/) {
		$counts{$1}++;
	}
}

for ( sort { $a cmp $b } keys %counts) {
	print "$_: $counts{$_}\n";
}

The diamond operator (<>) in the while loop is another example of a special operator in Perl. It will loop through the @ARGV array, which are the arguments passed into the script (in this case the file names), open the files, and read through the lines.

The if statement contains a regular expression which is implicitly checking against the $_ special variable, and the while loop sets $_ to each line as it loops through. In Perl, the $_ can usually be inferred and this is one such case.

The regular expression itself is doing the following:

The caret ^ is the character used to represent the start of a line, meaning that the match must begin with the start of a line.

When parentheses are used in a regular expression, the part of the string matched by the part of the regular expression inside the parentheses will be “captured” (i.e., stored in a temporary variable) if a match occurs. There can be multiple parentheses in a regular expression. The part of the string matching the first set of parentheses will be stored in the temporary variable $1, the second will be stored in $2, and so on. In the above example, there is only one set of parentheses, so $1 will be set to that match.

The match we’re checking for, \d{4}-\d{2}-\d{2}, consists of 4 digits followed by a dash, followed by 2 digits, followed by a dash, finally followed by 2 digits.

If we find that match, then we increment the %counts hash by one, where the key is the date that was matched. We don’t need to initialize the values the first time a key is found because Perl automatically sets the value to 0, so we can simply use the ++ operator to increment the counter for the date.

In Perl, you don't have to set a value the first time you use a key in a hash; Perl automatically sets this value to 0, so you can use the `++` operator to increment.

In the for statement, we are once again making use of the $_ special variable by not explicitly naming the value for each loop. Starting on the right side:

  • The keys %counts statement returns an array of the keys from the hash. These will be the dates that we previously encountered.

  • The sort function goes through the key array and uses the string comparison function cmp to sort the array in ascending order.

  • The resulting array is then used in the for loop where the output is printed out with the date, followed by a colon. Then we access the value from the %counts hash for the date (the number of times an error was logged), and append that, followed by a new line.

Common Functions

As with most modern programming languages, hashes and arrays are a big part of programming in Perl. Software developers may find data stored in one structure or the other, but may need to retrieve it in a specific format. Perl provides very concise and powerful functions to do this retrieval; functions with which experienced Perl developers must be familiar.

These questions are designed to test just how comfortable the candidate is with common Perl functions. Qualified candidates should have an understanding of common functions like map and grep. If the candidate solves the question using one function, ask them to solve it using the other function.

A junior-level programmer might write code that creates a separate array and then uses a `for` loop to add the value to a hash.

Q: Given an array, how would you get an array of just the unique elements?

A: The standard technique is as follows:

my %uniq_hash = map { $_ => 1 } @input;
my @uniq = keys %uniq_hash;

Here you are taking the @input array, and using map to create a hash with its keys set to the values of @input. Since a hash only allows for unique keys, there will be no duplicates. To get an array back, you just use the keys function to get the keys of the hash in array form.

Q: Write some code that prints ‘yes’ if the value 3 is in an array.

A: You could use the same procedure as above and then simply do:

my %uniq_hash = map { $_ => 1 } @input;
if ($uniq_hash{3}) { print 'yes'; }

This just checks the hash you created to see if there is a key set to 3 and, if there is, prints “yes”.

You could achieve the same effect with grep, which loops through the @input array and tests each value against your statement, as follows:

if (grep $_ eq 3, @input) { print 'yes'; }

While either approach will work, a developer would be better off using the first technique if multiple values need to be checked in order to avoid looping through the array multiple times. For a one-off check, though, this would not be an issue, in which case both ways would normally be acceptable.

Q: Given a string of key-value pairs in the example of the format key1=value1&key2=value2&key3=value3, how would you turn it into a hash?

A: While the answer is a single line, this question tests the candidate’s ability to understand the split function and how arrays are converted into hashes in Perl:

my %hash = split /[=&]/, $str;

The function split takes the input string and splits it into an array wherever the match occurs (in this case either an equal sign or ampersand). In this case, the resulting array would be [key1, value1, key2, value2, key3, value3].

Perl converts arrays to hashes by taking the first element as the key and second element as the value, then the third as the key and fourth as the value and so on.

Storing the result of the split function into a hash type, you will get the following:

{
	key1 => value1,
	key2 => value2,
	key3 => value3
}

There’s More Than One Way to Do It

Perl prides itself on providing multiple ways to accomplish the same software development, web development, or other programming tasks such as within Google’s mobile operating system, Android, on which Perl 5 can be installed. In front-end projects, Perl is well known by facilitating the use of scripts to create websites or parts of them to embed them in WordPress or HTML, CSS, Node.js. As such, keep an open mind about a candidate’s answers. Try to understand the reasoning behind their approach.

Some senior candidates in the United States or abroad may fully grasp the concise ways of programming and application development in Perl but choose to write out code in a more verbose way for easier readability. These developers might, for example, actively avoid using the special $_ variable because it takes time to figure out what it is actually referring to. They might therefore opt to use a named variable instead. The alternative might be a developer with a strong command of the language, but who writes code that is unreadable by junior-level developers.

By taking the time to understand the thinking behind the answers, you’ll gain a deep insight into the candidate’s thought process and find those that understand the long-term implications of the code that they write.

Top Perl Developers are in High Demand.

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